{
  "schema": "ml-prep/search@2",
  "items": [
    {
      "id": "mit-6-100l-finger-06",
      "title": "Bisection search finger exercise",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "binary-search",
        "loops",
        "conditionals"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "integer-arithmetic"
      ],
      "summary": "A small official exercise that separates binary-search reasoning from library use.",
      "path": "item/mit-6-100l-finger-06/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-06/"
    },
    {
      "id": "mit-6-100l-finger-11",
      "title": "List mutation and sorting finger exercise",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "python",
      "topic_title": "Python",
      "skills": [
        "python-sequence-semantics",
        "mutability"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 8,
      "prerequisites": [
        "lists"
      ],
      "summary": "Directly tests in-place mutation and ordering semantics.",
      "path": "item/mit-6-100l-finger-11/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-11/"
    },
    {
      "id": "mit-6-100l-finger-14",
      "title": "Dictionary selection finger exercise",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "dictionaries",
        "sets",
        "hash-map"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "dictionaries"
      ],
      "summary": "Uses dictionary iteration, filtering, and deterministic output ordering.",
      "path": "item/mit-6-100l-finger-14/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-14/"
    },
    {
      "id": "mit-6-100l-finger-15",
      "title": "Recursive power finger exercise",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "recursion",
      "topic_title": "Recursion",
      "skills": [
        "base-case",
        "recursive-trace",
        "recursive-implementation"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 7,
      "prerequisites": [
        "functions"
      ],
      "summary": "A minimal official check of base and recursive cases.",
      "path": "item/mit-6-100l-finger-15/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-15/"
    },
    {
      "id": "mit-6-100l-finger-16",
      "title": "Recursive flattening finger exercise",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "recursion",
      "topic_title": "Recursion",
      "skills": [
        "base-case",
        "recursive-implementation",
        "sequence-data-structures"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "recursion",
        "lists"
      ],
      "summary": "Adds recursive structural decomposition beyond a scalar recurrence.",
      "path": "item/mit-6-100l-finger-16/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-16/"
    },
    {
      "id": "mit-6-100l-finger-23",
      "title": "Asymptotic complexity finger exercise",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "python",
      "topic_title": "Python",
      "skills": [
        "complexity",
        "loops"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "loops"
      ],
      "summary": "Tests complexity from actual Python operations rather than memorized algorithm names.",
      "path": "item/mit-6-100l-finger-23/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-23/"
    },
    {
      "id": "google-mlcc-linear-regression-quiz",
      "title": "Linear regression knowledge check",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "regression",
      "topic_title": "Regression",
      "skills": [
        "linear-regression",
        "squared-loss",
        "gradient-update"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "algebra"
      ],
      "summary": "An authoritative interactive check of the regression objective and training loop.",
      "path": "item/google-mlcc-linear-regression-quiz/",
      "url": "https://mlprep.iwase.dev/item/google-mlcc-linear-regression-quiz/"
    },
    {
      "id": "google-mlcc-logistic-quiz",
      "title": "Logistic regression knowledge check",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "logistic-regression",
        "cross-entropy",
        "optimization-regularization"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "probability"
      ],
      "summary": "Checks probability interpretation, loss, and regularization on the official Google course.",
      "path": "item/google-mlcc-logistic-quiz/",
      "url": "https://mlprep.iwase.dev/item/google-mlcc-logistic-quiz/"
    },
    {
      "id": "google-mlcc-classification-quiz",
      "title": "Classification metrics knowledge check",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "confusion-matrix",
        "accuracy",
        "precision-recall",
        "decision-boundary",
        "classification-thresholds"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "fractions"
      ],
      "summary": "Authoritative questions on threshold-dependent classification metrics.",
      "path": "item/google-mlcc-classification-quiz/",
      "url": "https://mlprep.iwase.dev/item/google-mlcc-classification-quiz/"
    },
    {
      "id": "google-mlcc-overfitting-quiz",
      "title": "Generalization and overfitting knowledge check",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "theory",
      "topic_title": "Theory",
      "skills": [
        "generalization",
        "overfitting",
        "train-validation-test",
        "model-complexity",
        "optimization-regularization"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "training-loss"
      ],
      "summary": "Covers the evaluation distinctions most often confused under time pressure.",
      "path": "item/google-mlcc-overfitting-quiz/",
      "url": "https://mlprep.iwase.dev/item/google-mlcc-overfitting-quiz/"
    },
    {
      "id": "google-mlcc-neural-network-quiz",
      "title": "Neural-network knowledge check",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "neural-networks",
      "topic_title": "Neural Networks",
      "skills": [
        "forward-pass",
        "activations",
        "backpropagation",
        "neural-network-losses"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "linear-models"
      ],
      "summary": "A concise official check of architecture, activations, and training.",
      "path": "item/google-mlcc-neural-network-quiz/",
      "url": "https://mlprep.iwase.dev/item/google-mlcc-neural-network-quiz/"
    },
    {
      "id": "leetcode-20-valid-parentheses",
      "title": "Valid Parentheses",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "stack",
        "conditionals"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 12,
      "prerequisites": [
        "strings"
      ],
      "summary": "A standard stack invariant problem with immediate judge feedback on malformed nesting and edge cases.",
      "path": "item/leetcode-20-valid-parentheses/",
      "url": "https://mlprep.iwase.dev/item/leetcode-20-valid-parentheses/"
    },
    {
      "id": "leetcode-215-kth-largest",
      "title": "Kth Largest Element in an Array",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "heap",
        "complexity"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 20,
      "prerequisites": [
        "arrays",
        "priority-queues"
      ],
      "summary": "Requires selecting an appropriate heap or selection strategy under an explicit complexity target and provides judge feedback.",
      "path": "item/leetcode-215-kth-largest/",
      "url": "https://mlprep.iwase.dev/item/leetcode-215-kth-largest/"
    },
    {
      "id": "leetcode-704-binary-search",
      "title": "Binary Search",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "binary-search",
        "conditionals",
        "loops"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "sorted-arrays"
      ],
      "summary": "Tests interval invariants and termination on a canonical sorted-array search with judge feedback.",
      "path": "item/leetcode-704-binary-search/",
      "url": "https://mlprep.iwase.dev/item/leetcode-704-binary-search/"
    },
    {
      "id": "leetcode-752-open-the-lock",
      "title": "Open the Lock",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "queue",
        "bfs",
        "dictionaries",
        "sets"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 25,
      "prerequisites": [
        "graphs",
        "shortest-path"
      ],
      "summary": "Models an implicit state graph and requires BFS with visited-state handling; submissions receive judge feedback.",
      "path": "item/leetcode-752-open-the-lock/",
      "url": "https://mlprep.iwase.dev/item/leetcode-752-open-the-lock/"
    },
    {
      "id": "leetcode-200-number-of-islands",
      "title": "Number of Islands",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "dfs",
        "bfs",
        "queue",
        "recursive-implementation"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 25,
      "prerequisites": [
        "grids",
        "graph-traversal"
      ],
      "summary": "Uses recursive or iterative flood fill to test traversal state, base cases, and component counting with judge feedback.",
      "path": "item/leetcode-200-number-of-islands/",
      "url": "https://mlprep.iwase.dev/item/leetcode-200-number-of-islands/"
    },
    {
      "id": "mit-18-02sc-f2010-exam2-q1",
      "title": "Gradient, tangent plane, linearization, and directional derivative",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "gradient",
        "directional-derivative"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 12,
      "prerequisites": [
        "partial-derivatives"
      ],
      "summary": "A fast diagnostic of the multivariable differential concepts most likely to transfer to ML.",
      "path": "item/mit-18-02sc-f2010-exam2-q1/",
      "url": "https://mlprep.iwase.dev/item/mit-18-02sc-f2010-exam2-q1/"
    },
    {
      "id": "mit-18-02sc-f2010-exam2-q3",
      "title": "Critical points and constrained domain boundaries",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "calculus-stationary-points",
        "unconstrained-optimization"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 14,
      "prerequisites": [
        "partial-derivatives",
        "quadratic-functions"
      ],
      "summary": "Separates local critical-point classification from optimization over a constrained region.",
      "path": "item/mit-18-02sc-f2010-exam2-q3/",
      "url": "https://mlprep.iwase.dev/item/mit-18-02sc-f2010-exam2-q3/"
    },
    {
      "id": "mit-18-02sc-f2010-exam2-q4",
      "title": "Multivariable chain rule under a change of variables",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "multivariable-chain-rule",
        "partial-derivatives"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "partial-derivatives"
      ],
      "summary": "Tests symbolic chain-rule bookkeeping that directly supports backpropagation and reparameterization.",
      "path": "item/mit-18-02sc-f2010-exam2-q4/",
      "url": "https://mlprep.iwase.dev/item/mit-18-02sc-f2010-exam2-q4/"
    },
    {
      "id": "mit-18-02sc-f2010-exam2-q5",
      "title": "Lagrange multiplier equations and tangent geometry",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "constrained-optimization"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "gradient",
        "implicit-surfaces"
      ],
      "summary": "Focuses on setting up constrained optimization and interpreting the shared normal direction.",
      "path": "item/mit-18-02sc-f2010-exam2-q5/",
      "url": "https://mlprep.iwase.dev/item/mit-18-02sc-f2010-exam2-q5/"
    },
    {
      "id": "mit-18-02sc-f2010-exam2-q6",
      "title": "Total differentials and implicit differentiation",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "implicit-differentiation",
        "linear-systems"
      ],
      "priority": "supplementary",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "partial-derivatives"
      ],
      "summary": "Checks whether local differential constraints can be combined and solved without treating variables as independent.",
      "path": "item/mit-18-02sc-f2010-exam2-q6/",
      "url": "https://mlprep.iwase.dev/item/mit-18-02sc-f2010-exam2-q6/"
    },
    {
      "id": "mit-18-05-s2022-exam1-q1b",
      "title": "Events, unions, and conditional probability",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "event-algebra",
        "inclusion-exclusion",
        "conditional-probability"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 6,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "A compact check of whether event notation and conditioning are operational rather than merely familiar.",
      "path": "item/mit-18-05-s2022-exam1-q1b/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam1-q1b/"
    },
    {
      "id": "mit-18-05-s2022-exam1-q3",
      "title": "Joint tables, Bayes rule, and independence",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "bayes-rule",
        "probabilistic-independence"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 14,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "Uses one finite model to test joint and marginal probabilities, reverse conditioning, and independence.",
      "path": "item/mit-18-05-s2022-exam1-q3/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam1-q3/"
    },
    {
      "id": "mit-18-05-s2022-exam1-q4",
      "title": "Diagnostic testing with base rates",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "bayes-rule",
        "conditional-probability"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 8,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "A short, discriminative Bayes calculation whose interpretation transfers directly to ML evaluation.",
      "path": "item/mit-18-05-s2022-exam1-q4/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam1-q4/"
    },
    {
      "id": "mit-18-05-s2022-exam1-q5",
      "title": "Joint density, moments, covariance, and correlation",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "joint-distributions",
        "marginal-distributions",
        "conditional-distributions",
        "probabilistic-independence",
        "expectation",
        "variance"
      ],
      "priority": "core",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 24,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "Integrates continuous probability, moments, dependence, and a geometric integration region in one coherent problem.",
      "path": "item/mit-18-05-s2022-exam1-q5/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam1-q5/"
    },
    {
      "id": "mit-18-05-s2022-exam1-q6",
      "title": "Central limit theorem for an aggregate",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "central-limit-theorem",
        "sums-of-random-variables"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "Tests whether the learner can propagate mean and variance and standardize an aggregate.",
      "path": "item/mit-18-05-s2022-exam1-q6/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam1-q6/"
    },
    {
      "id": "mit-18-05-s2022-exam2-i2",
      "title": "Type I error, Type II error, and power",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "null-alternative",
        "type-i-error",
        "type-ii-error",
        "statistical-power"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 5,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "A rapid conceptual diagnostic that catches common confusion among significance, power, and error rates.",
      "path": "item/mit-18-05-s2022-exam2-i2/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam2-i2/"
    },
    {
      "id": "mit-18-05-s2022-exam2-ii1",
      "title": "Maximum likelihood estimation from a density",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "likelihood",
        "maximum-likelihood"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 12,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "Requires constructing and differentiating a likelihood rather than quoting an estimator.",
      "path": "item/mit-18-05-s2022-exam2-ii1/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam2-ii1/"
    },
    {
      "id": "mit-18-05-s2022-exam2-ii2",
      "title": "Bayesian posterior density and normalization",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "bayesian-updating"
      ],
      "priority": "core",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 15,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "Tests likelihood construction, prior multiplication, and posterior normalization in a finite-outcome model.",
      "path": "item/mit-18-05-s2022-exam2-ii2/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam2-ii2/"
    },
    {
      "id": "mit-18-05-s2022-exam2-ii4",
      "title": "One-sided test, critical value, and p-value",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "null-alternative",
        "p-values",
        "critical-regions"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 12,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "Connects a rejection region, significance level, observed statistic, and p-value without relying on one mnemonic.",
      "path": "item/mit-18-05-s2022-exam2-ii4/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam2-ii4/"
    },
    {
      "id": "mit-18-05-s2022-exam2-ii5",
      "title": "Chi-square test for a contingency table",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "goodness-of-fit",
        "chi-square"
      ],
      "priority": "core",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 18,
      "prerequisites": [
        "basic-algebra"
      ],
      "summary": "Checks end-to-end statistical reasoning from hypotheses through expected counts to a justified decision.",
      "path": "item/mit-18-05-s2022-exam2-ii5/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-exam2-ii5/"
    },
    {
      "id": "mit-18-06-s2010-exam1-q2",
      "title": "Nullspace, column space, pivots, and block structure",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "matrix-operations",
        "linear-systems",
        "row-reduction",
        "subspaces",
        "rank",
        "rank-nullity"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 14,
      "prerequisites": [
        "linear-systems",
        "reduced-row-echelon-form"
      ],
      "summary": "Distinguishes procedural row reduction from geometric understanding of the four fundamental subspaces.",
      "path": "item/mit-18-06-s2010-exam1-q2/",
      "url": "https://mlprep.iwase.dev/item/mit-18-06-s2010-exam1-q2/"
    },
    {
      "id": "mit-18-06-s2010-exam2-q1",
      "title": "Projection matrix as geometry and spectrum",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "projection",
        "eigenvalues",
        "eigenvectors"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 15,
      "prerequisites": [
        "orthogonality",
        "outer-products"
      ],
      "summary": "Connects a projection formula to its subspaces and eigenstructure, a high-value ML pattern.",
      "path": "item/mit-18-06-s2010-exam2-q1/",
      "url": "https://mlprep.iwase.dev/item/mit-18-06-s2010-exam2-q1/"
    },
    {
      "id": "mit-18-06-s2010-exam2-q2",
      "title": "Least squares, QR, and orthonormal projection",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "least-squares",
        "normal-equations",
        "qr",
        "projection",
        "orthogonality"
      ],
      "priority": "core",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 18,
      "prerequisites": [
        "orthogonality",
        "matrix-inverse"
      ],
      "summary": "Tests the derivation and interpretation of least squares rather than formula recall alone.",
      "path": "item/mit-18-06-s2010-exam2-q2/",
      "url": "https://mlprep.iwase.dev/item/mit-18-06-s2010-exam2-q2/"
    },
    {
      "id": "mit-18-06-s2010-exam3-q1",
      "title": "Symmetry, orthogonality, and eigenspaces",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "symmetric-matrices",
        "eigenvalues",
        "eigenvectors",
        "diagonalization"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 16,
      "prerequisites": [
        "outer-products",
        "orthogonal-complements"
      ],
      "summary": "Uses a structured matrix to test proof, geometry, multiplicity, and trace in one compact question.",
      "path": "item/mit-18-06-s2010-exam3-q1/",
      "url": "https://mlprep.iwase.dev/item/mit-18-06-s2010-exam3-q1/"
    },
    {
      "id": "mit-18-06-s2010-exam3-q2",
      "title": "Positive definite and semidefinite transformations",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "positive-definite-semidefinite",
        "quadratic-forms"
      ],
      "priority": "core",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 14,
      "prerequisites": [
        "eigenvalues",
        "quadratic-forms"
      ],
      "summary": "Exercises three interchangeable tests for positive definiteness and a useful block-matrix argument.",
      "path": "item/mit-18-06-s2010-exam3-q2/",
      "url": "https://mlprep.iwase.dev/item/mit-18-06-s2010-exam3-q2/"
    },
    {
      "id": "mit-18-06-s2010-exam3-q3c",
      "title": "Singular value decomposition from the Gram matrix",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "svd",
        "orthogonality"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 10,
      "prerequisites": [
        "eigenvalues",
        "orthogonality"
      ],
      "summary": "A compact check that the learner can construct an SVD from the eigendecomposition of a Gram matrix.",
      "path": "item/mit-18-06-s2010-exam3-q3c/",
      "url": "https://mlprep.iwase.dev/item/mit-18-06-s2010-exam3-q3c/"
    },
    {
      "id": "mit-6-036-s2018-final-q9",
      "title": "Convolutional representation and detector design",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "convolution",
      "topic_title": "Convolution",
      "skills": [
        "convolution-operation",
        "output-shape",
        "receptive-field"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 18,
      "prerequisites": [
        "matrix-indexing",
        "relu"
      ],
      "summary": "Requires an actual convolution and composes small filters into a deeper detector instead of testing shape recall alone.",
      "path": "item/mit-6-036-s2018-final-q9/",
      "url": "https://mlprep.iwase.dev/item/mit-6-036-s2018-final-q9/"
    },
    {
      "id": "mit-6-036-s2019-final-q4",
      "title": "CNN shapes, pooling, and backpropagation",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "convolution",
      "topic_title": "Convolution",
      "skills": [
        "convolution-operation",
        "output-shape",
        "convolution-parameter-count",
        "pooling"
      ],
      "priority": "supplementary",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 25,
      "prerequisites": [
        "backpropagation",
        "max-pooling",
        "sgd"
      ],
      "summary": "Integrates convolutional shapes, loss choice, differentiation through convolution and pooling, and an SGD debugging decision.",
      "path": "item/mit-6-036-s2019-final-q4/",
      "url": "https://mlprep.iwase.dev/item/mit-6-036-s2019-final-q4/"
    },
    {
      "id": "mit-6-036-s2019-midterm-q5",
      "title": "Learning as optimization",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "optimization",
      "topic_title": "Optimization",
      "skills": [
        "objective-functions",
        "optimization-convexity",
        "optimization-diagnostics",
        "optimization-stationary-points"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 18,
      "prerequisites": [
        "derivatives",
        "gradient-descent",
        "loss-functions"
      ],
      "summary": "Derives an update and distinguishes slow, oscillating, and divergent learning-rate behavior from objective geometry.",
      "path": "item/mit-6-036-s2019-midterm-q5/",
      "url": "https://mlprep.iwase.dev/item/mit-6-036-s2019-midterm-q5/"
    },
    {
      "id": "mit-6-036-s2019-midterm-q4",
      "title": "Diagnose model evaluation failures",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "theory",
      "topic_title": "Theory",
      "skills": [
        "bias-variance",
        "generalization",
        "overfitting",
        "train-validation-test",
        "model-complexity"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 15,
      "prerequisites": [
        "classification-metrics"
      ],
      "summary": "Uses observed train and held-out behavior to separate overfitting, insufficient expressivity, data scarcity, and distribution shift.",
      "path": "item/mit-6-036-s2019-midterm-q4/",
      "url": "https://mlprep.iwase.dev/item/mit-6-036-s2019-midterm-q4/"
    },
    {
      "id": "mit-6-100l-finger-05",
      "title": "Even-indexed characters finger exercise",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "control-flow",
      "topic_title": "Control Flow",
      "skills": [
        "conditionals",
        "loops",
        "strings"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 5,
      "prerequisites": [
        "string-indexing"
      ],
      "summary": "Uses a compact string traversal to test index parity, loop state, and output construction.",
      "path": "item/mit-6-100l-finger-05/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-05/"
    },
    {
      "id": "mit-6-100l-finger-08",
      "title": "Compare character sets in two strings",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "control-flow",
      "topic_title": "Control Flow",
      "skills": [
        "conditionals",
        "loops",
        "strings"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 6,
      "prerequisites": [
        "membership"
      ],
      "summary": "Tests bidirectional membership reasoning rather than only one pass over one string.",
      "path": "item/mit-6-100l-finger-08/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-08/"
    },
    {
      "id": "mit-6-100l-finger-17",
      "title": "Circle class and value equality",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "python",
      "topic_title": "Python",
      "skills": [
        "classes",
        "value-equality",
        "python-syntax",
        "functions"
      ],
      "priority": "supplementary",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 12,
      "prerequisites": [
        "methods",
        "object-state"
      ],
      "summary": "Exercises object state, accessors, mutation, and explicit value equality through a small class contract.",
      "path": "item/mit-6-100l-finger-17/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-17/"
    },
    {
      "id": "mit-6-100l-finger-19",
      "title": "Stack subclass implementation",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "stack",
        "classes",
        "sequence-data-structures"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 15,
      "prerequisites": [
        "lists",
        "methods"
      ],
      "summary": "Implements a LIFO abstraction while distinguishing inherited container behavior from stack-specific removal.",
      "path": "item/mit-6-100l-finger-19/",
      "url": "https://mlprep.iwase.dev/item/mit-6-100l-finger-19/"
    },
    {
      "id": "mit-18-01sc-f2010-final-foundations",
      "title": "Single-variable calculus foundation check",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "limits",
        "continuity",
        "single-variable-differentiation",
        "single-variable-integration",
        "taylor-approximation"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 24,
      "prerequisites": [
        "polynomials"
      ],
      "summary": "Uses official exam questions to check differentiation, a limit, definite integration, and Taylor approximation independently.",
      "path": "item/mit-18-01sc-f2010-final-foundations/",
      "url": "https://mlprep.iwase.dev/item/mit-18-01sc-f2010-final-foundations/"
    },
    {
      "id": "mit-18-05-s2022-pset11-q1",
      "title": "Confidence intervals with known and unknown variance",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "confidence-intervals",
        "standard-error",
        "sampling-distributions"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "external",
      "estimated_minutes": 14,
      "prerequisites": [
        "gaussian-distribution"
      ],
      "summary": "Contrasts t and z intervals on the same data and extends the calculation to sample-size planning.",
      "path": "item/mit-18-05-s2022-pset11-q1/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-pset11-q1/"
    },
    {
      "id": "mit-18-05-s2022-pset6-q2",
      "title": "Simple linear regression from Gaussian maximum likelihood",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "simple-linear-regression",
        "maximum-likelihood",
        "likelihood"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 25,
      "prerequisites": [
        "gaussian-distribution",
        "partial-derivatives"
      ],
      "summary": "Derives a fitted line from an explicit Gaussian error model, linking regression, likelihood, and least squares.",
      "path": "item/mit-18-05-s2022-pset6-q2/",
      "url": "https://mlprep.iwase.dev/item/mit-18-05-s2022-pset6-q2/"
    },
    {
      "id": "original-la-foundations",
      "title": "Matrix fundamentals under time pressure",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "matrix-operations",
        "inverse",
        "determinant",
        "trace",
        "matrix-norms"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "matrix-arithmetic"
      ],
      "summary": "Original practice item.",
      "path": "item/original-la-foundations/",
      "url": "https://mlprep.iwase.dev/item/original-la-foundations/"
    },
    {
      "id": "original-la-basis-change",
      "title": "Basis, dimension, and coordinates",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "linear-independence",
        "basis-dimension",
        "change-of-basis"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "linear-combinations"
      ],
      "summary": "Original practice item.",
      "path": "item/original-la-basis-change/",
      "url": "https://mlprep.iwase.dev/item/original-la-basis-change/"
    },
    {
      "id": "original-la-low-rank",
      "title": "Low-rank error and explained variance",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "svd",
        "low-rank-approximation",
        "pca-via-svd"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "singular-values"
      ],
      "summary": "Original practice item.",
      "path": "item/original-la-low-rank/",
      "url": "https://mlprep.iwase.dev/item/original-la-low-rank/"
    },
    {
      "id": "original-calc-jacobian",
      "title": "Jacobian and chain rule",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "partial-derivatives",
        "jacobian",
        "multivariable-chain-rule",
        "gradient"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 10,
      "prerequisites": [
        "partial-derivatives"
      ],
      "summary": "Original practice item.",
      "path": "item/original-calc-jacobian/",
      "url": "https://mlprep.iwase.dev/item/original-calc-jacobian/"
    },
    {
      "id": "original-calc-matrix",
      "title": "Matrix gradient and Hessian",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "matrix-calculus",
        "gradient",
        "hessian",
        "calculus-convexity"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 10,
      "prerequisites": [
        "matrix-multiplication",
        "chain-rule"
      ],
      "summary": "Original practice item.",
      "path": "item/original-calc-matrix/",
      "url": "https://mlprep.iwase.dev/item/original-calc-matrix/"
    },
    {
      "id": "original-prob-distributions",
      "title": "Recognize distribution moments",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "discrete-random-variables",
        "pmf",
        "cdf",
        "continuous-random-variables",
        "pdf",
        "named-distributions",
        "sums-of-random-variables",
        "expectation",
        "variance"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "random-variables"
      ],
      "summary": "Original practice item.",
      "path": "item/original-prob-distributions/",
      "url": "https://mlprep.iwase.dev/item/original-prob-distributions/"
    },
    {
      "id": "original-prob-total-variance",
      "title": "Conditional expectation and total variance",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "conditional-expectation",
        "law-total-expectation",
        "law-total-variance",
        "expectation",
        "variance"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "conditional-probability"
      ],
      "summary": "Original practice item.",
      "path": "item/original-prob-total-variance/",
      "url": "https://mlprep.iwase.dev/item/original-prob-total-variance/"
    },
    {
      "id": "original-prob-gaussian",
      "title": "Linear transform of a multivariate Gaussian",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "multivariate-gaussian",
        "transformations",
        "covariance",
        "correlation"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "matrix-multiplication",
        "gaussian-distribution"
      ],
      "summary": "Original practice item.",
      "path": "item/original-prob-gaussian/",
      "url": "https://mlprep.iwase.dev/item/original-prob-gaussian/"
    },
    {
      "id": "original-prob-foundations",
      "title": "Counting, total probability, and independence",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "counting",
        "conditional-probability",
        "probabilistic-independence"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "fractions"
      ],
      "summary": "Original practice item.",
      "path": "item/original-prob-foundations/",
      "url": "https://mlprep.iwase.dev/item/original-prob-foundations/"
    },
    {
      "id": "original-prob-lln",
      "title": "LLN versus CLT",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "law-of-large-numbers",
        "central-limit-theorem"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "expectation",
        "variance"
      ],
      "summary": "Original practice item.",
      "path": "item/original-prob-lln/",
      "url": "https://mlprep.iwase.dev/item/original-prob-lln/"
    },
    {
      "id": "original-stats-estimator",
      "title": "Bias, variance, MSE, and consistency",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "samples",
        "sample-statistics",
        "sampling-distributions",
        "estimator-bias",
        "estimator-variance",
        "mean-squared-error",
        "consistency",
        "standard-error"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "expectation",
        "variance"
      ],
      "summary": "Original practice item.",
      "path": "item/original-stats-estimator/",
      "url": "https://mlprep.iwase.dev/item/original-stats-estimator/"
    },
    {
      "id": "original-stats-mom-map",
      "title": "Method of moments and Bayesian updating",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "method-of-moments",
        "map",
        "bayesian-updating",
        "likelihood"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 10,
      "prerequisites": [
        "exponential-distribution",
        "beta-distribution"
      ],
      "summary": "Original practice item.",
      "path": "item/original-stats-mom-map/",
      "url": "https://mlprep.iwase.dev/item/original-stats-mom-map/"
    },
    {
      "id": "original-ml-regression",
      "title": "Linear regression objective and gradient",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "regression",
      "topic_title": "Regression",
      "skills": [
        "linear-regression",
        "squared-loss",
        "regression-gradient"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "matrix-multiplication",
        "derivatives"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-regression/",
      "url": "https://mlprep.iwase.dev/item/original-ml-regression/"
    },
    {
      "id": "original-ml-logistic",
      "title": "Logistic probability and cross-entropy",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "logistic-regression",
        "cross-entropy",
        "decision-boundary",
        "classification-thresholds"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "logarithms"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-logistic/",
      "url": "https://mlprep.iwase.dev/item/original-ml-logistic/"
    },
    {
      "id": "original-ml-metrics",
      "title": "Classification metrics from counts",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "confusion-matrix",
        "accuracy",
        "precision-recall"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "fractions"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-metrics/",
      "url": "https://mlprep.iwase.dev/item/original-ml-metrics/"
    },
    {
      "id": "original-ml-gd",
      "title": "Gradient descent on a quadratic",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "gradient-descent",
      "topic_title": "Gradient Descent",
      "skills": [
        "gradient-update",
        "learning-rate",
        "convergence"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "derivatives"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-gd/",
      "url": "https://mlprep.iwase.dev/item/original-ml-gd/"
    },
    {
      "id": "original-ml-sgd",
      "title": "Full gradient versus stochastic gradient",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "gradient-descent",
      "topic_title": "Gradient Descent",
      "skills": [
        "gradient-update",
        "sgd",
        "convergence"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "expectation"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-sgd/",
      "url": "https://mlprep.iwase.dev/item/original-ml-sgd/"
    },
    {
      "id": "original-ml-pca",
      "title": "PCA direction and explained variance",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "dimensionality-reduction",
      "topic_title": "Dimensionality Reduction",
      "skills": [
        "pca-objective",
        "centering",
        "covariance-eigendecomposition",
        "explained-variance"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "eigenvalues"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-pca/",
      "url": "https://mlprep.iwase.dev/item/original-ml-pca/"
    },
    {
      "id": "original-ml-kmeans",
      "title": "One k-means assignment and update",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "unsupervised-learning",
      "topic_title": "Unsupervised Learning",
      "skills": [
        "k-means",
        "clustering-objective"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "squared-distance"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-kmeans/",
      "url": "https://mlprep.iwase.dev/item/original-ml-kmeans/"
    },
    {
      "id": "original-ml-gmm",
      "title": "Mixture responsibilities and EM",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "unsupervised-learning",
      "topic_title": "Unsupervised Learning",
      "skills": [
        "gaussian-mixtures",
        "expectation-maximization",
        "clustering-objective"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "bayes-rule"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-gmm/",
      "url": "https://mlprep.iwase.dev/item/original-ml-gmm/"
    },
    {
      "id": "original-ml-forward-backprop",
      "title": "Forward pass and backpropagation",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "neural-networks",
      "topic_title": "Neural Networks",
      "skills": [
        "forward-pass",
        "activations",
        "neural-network-chain-rule",
        "backpropagation",
        "neural-network-losses"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "chain-rule"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-forward-backprop/",
      "url": "https://mlprep.iwase.dev/item/original-ml-forward-backprop/"
    },
    {
      "id": "original-ml-network-params",
      "title": "Dense-network parameter count",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "neural-networks",
      "topic_title": "Neural Networks",
      "skills": [
        "dense-network-parameter-count"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "matrix-shapes"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-network-params/",
      "url": "https://mlprep.iwase.dev/item/original-ml-network-params/"
    },
    {
      "id": "original-ml-convolution",
      "title": "Convolution output shape and parameters",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "convolution",
      "topic_title": "Convolution",
      "skills": [
        "output-shape",
        "padding",
        "stride",
        "convolution-parameter-count"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "integer-arithmetic"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-convolution/",
      "url": "https://mlprep.iwase.dev/item/original-ml-convolution/"
    },
    {
      "id": "original-ml-regularization",
      "title": "Lasso versus ridge penalties",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "optimization",
      "topic_title": "Optimization",
      "skills": [
        "optimization-regularization",
        "objective-functions",
        "model-complexity",
        "generalization"
      ],
      "priority": "core",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "norms"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-regularization/",
      "url": "https://mlprep.iwase.dev/item/original-ml-regularization/"
    },
    {
      "id": "original-ml-finite-class-bound",
      "title": "Read a finite-class generalization bound",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "theory",
      "topic_title": "Theory",
      "skills": [
        "generalization",
        "model-complexity"
      ],
      "priority": "stretch",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "logarithms",
        "probability"
      ],
      "summary": "Original practice item.",
      "path": "item/original-ml-finite-class-bound/",
      "url": "https://mlprep.iwase.dev/item/original-ml-finite-class-bound/"
    },
    {
      "id": "original-py-alias-copy",
      "title": "Aliasing and shallow copy",
      "collection": "practice",
      "area": "programming",
      "area_title": "Programming",
      "topic": "python",
      "topic_title": "Python",
      "skills": [
        "python-sequence-semantics",
        "mutability",
        "aliasing",
        "shallow-copy"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "lists"
      ],
      "summary": "Original practice item.",
      "path": "item/original-py-alias-copy/",
      "url": "https://mlprep.iwase.dev/item/original-py-alias-copy/"
    },
    {
      "id": "pml-book1-ex5.1",
      "title": "Reject option in classifiers",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "decision-boundary",
        "classification-thresholds"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 12,
      "prerequisites": [
        "conditional-probability",
        "expected-loss"
      ],
      "summary": "Derives a confidence-dependent classification and rejection rule from explicit costs and posterior class probabilities.",
      "path": "item/pml-book1-ex5.1/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex5.1/"
    },
    {
      "id": "pml-book1-ex11.2",
      "title": "Centering and ridge regression",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "regression",
      "topic_title": "Regression",
      "skills": [
        "linear-regression",
        "normal-equations",
        "regression-regularization"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 15,
      "prerequisites": [
        "matrix-multiplication",
        "centering"
      ],
      "summary": "Connects centering, the ridge objective, the intercept, and normal equations in one derivation.",
      "path": "item/pml-book1-ex11.2/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex11.2/"
    },
    {
      "id": "pml-book1-ex4.5",
      "title": "BIC for a two-dimensional discrete distribution",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "theory",
      "topic_title": "Theory",
      "skills": [
        "generalization",
        "overfitting",
        "model-complexity"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 20,
      "prerequisites": [
        "maximum-likelihood",
        "logarithms",
        "cross-validation"
      ],
      "summary": "Compares nested models using fit, leave-one-out behavior, parameter count, and a complexity penalty.",
      "path": "item/pml-book1-ex4.5/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex4.5/"
    },
    {
      "id": "pml-book1-ex20.3",
      "title": "Deriving the second principal component",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "dimensionality-reduction",
      "topic_title": "Dimensionality Reduction",
      "skills": [
        "pca-objective",
        "covariance-eigendecomposition"
      ],
      "priority": "core",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 18,
      "prerequisites": [
        "eigenvectors",
        "lagrange-multipliers",
        "matrix-calculus"
      ],
      "summary": "Connects the constrained PCA reconstruction objective to the covariance eigenvector with the second-largest eigenvalue.",
      "path": "item/pml-book1-ex20.3/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex20.3/"
    },
    {
      "id": "pml-book1-ex10.1",
      "title": "Gradient and Hessian of multinomial logistic regression",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "logistic-regression",
        "cross-entropy"
      ],
      "priority": "supplementary",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 20,
      "prerequisites": [
        "softmax",
        "chain-rule",
        "matrix-calculus"
      ],
      "summary": "Derives the first- and second-order structure of multiclass logistic loss.",
      "path": "item/pml-book1-ex10.1/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex10.1/"
    },
    {
      "id": "pml-book1-ex13.1",
      "title": "Backpropagation for a multilayer perceptron",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "neural-networks",
      "topic_title": "Neural Networks",
      "skills": [
        "forward-pass",
        "activations",
        "neural-network-chain-rule",
        "backpropagation",
        "neural-network-losses"
      ],
      "priority": "core",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 20,
      "prerequisites": [
        "softmax",
        "cross-entropy",
        "matrix-calculus",
        "relu"
      ],
      "summary": "Derives layer errors, parameter gradients, and the input gradient for a one-hidden-layer classifier.",
      "path": "item/pml-book1-ex13.1/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex13.1/"
    },
    {
      "id": "pml-book1-ex11.4",
      "title": "Reducing elastic net to lasso",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "optimization",
      "topic_title": "Optimization",
      "skills": [
        "objective-functions",
        "optimization-regularization"
      ],
      "priority": "supplementary",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 15,
      "prerequisites": [
        "l1-norm",
        "l2-norm",
        "linear-regression"
      ],
      "summary": "Transforms a mixed regularization objective into a standard lasso problem on augmented data.",
      "path": "item/pml-book1-ex11.4/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex11.4/"
    },
    {
      "id": "pml-book1-ex20.1",
      "title": "Expectation-maximization for factor analysis",
      "collection": "practice",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "unsupervised-learning",
      "topic_title": "Unsupervised Learning",
      "skills": [
        "expectation-maximization"
      ],
      "priority": "supplementary",
      "difficulty": "hard",
      "origin": "external",
      "estimated_minutes": 30,
      "prerequisites": [
        "multivariate-gaussian",
        "matrix-calculus",
        "latent-variables"
      ],
      "summary": "Derives E- and M-step updates for a latent Gaussian factor model.",
      "path": "item/pml-book1-ex20.1/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex20.1/"
    },
    {
      "id": "harvard-stat110-f2011-sp5-continuous-q1",
      "title": "Lognormal transformation by the CDF method",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "continuous-random-variables",
        "pdf",
        "cdf",
        "transformations"
      ],
      "priority": "supplementary",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 12,
      "prerequisites": [
        "normal-distribution",
        "chain-rule"
      ],
      "summary": "A compact test of transforming a continuous random variable using a CDF before differentiating for the density.",
      "path": "item/harvard-stat110-f2011-sp5-continuous-q1/",
      "url": "https://mlprep.iwase.dev/item/harvard-stat110-f2011-sp5-continuous-q1/"
    },
    {
      "id": "pml-book1-ex2.9",
      "title": "Bayes rule and diagnostic evidence",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "total-probability",
        "bayes-rule",
        "conditional-probability"
      ],
      "priority": "supplementary",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 12,
      "prerequisites": [
        "conditional-probability"
      ],
      "summary": "Connects Bayes rule to evidence interpretation and exposes the common confusion between a likelihood and a posterior.",
      "path": "item/pml-book1-ex2.9/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex2.9/"
    },
    {
      "id": "pml-book1-ex3.4",
      "title": "Linear transformations and quadratic expectations",
      "collection": "practice",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "covariance",
        "correlation"
      ],
      "priority": "supplementary",
      "difficulty": "medium",
      "origin": "external",
      "estimated_minutes": 15,
      "prerequisites": [
        "expectation",
        "covariance",
        "matrix-multiplication"
      ],
      "summary": "Exercises the matrix identities behind transformed covariance and expected quadratic forms used throughout machine learning.",
      "path": "item/pml-book1-ex3.4/",
      "url": "https://mlprep.iwase.dev/item/pml-book1-ex3.4/"
    },
    {
      "id": "ml-screen-regression-foundation-gradient",
      "title": "Squared loss and gradient",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "regression",
      "topic_title": "Regression",
      "skills": [
        "linear-regression",
        "squared-loss",
        "regression-gradient"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "basic-derivatives",
        "vector-arithmetic"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-regression-foundation-gradient/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-regression-foundation-gradient/"
    },
    {
      "id": "ml-screen-regression-standard-normal-equations",
      "title": "Solve normal equations",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "regression",
      "topic_title": "Regression",
      "skills": [
        "linear-regression",
        "squared-loss",
        "normal-equations"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "matrix-multiplication",
        "linear-systems"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-regression-standard-normal-equations/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-regression-standard-normal-equations/"
    },
    {
      "id": "ml-screen-regression-advanced-ridge",
      "title": "One-dimensional ridge estimate",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "regression",
      "topic_title": "Regression",
      "skills": [
        "linear-regression",
        "normal-equations",
        "regression-regularization"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 10,
      "prerequisites": [
        "derivatives",
        "least-squares"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-regression-advanced-ridge/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-regression-advanced-ridge/"
    },
    {
      "id": "ml-screen-classification-foundation-logistic",
      "title": "Logistic probability and loss",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "logistic-regression",
        "cross-entropy",
        "decision-boundary",
        "classification-thresholds"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "logarithms",
        "sigmoid"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-classification-foundation-logistic/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-classification-foundation-logistic/"
    },
    {
      "id": "ml-screen-classification-standard-metrics",
      "title": "Metrics from a confusion matrix",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "confusion-matrix",
        "accuracy",
        "precision-recall"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "fractions"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-classification-standard-metrics/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-classification-standard-metrics/"
    },
    {
      "id": "ml-screen-classification-advanced-cost-threshold",
      "title": "Cost-sensitive threshold",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "classification",
      "topic_title": "Classification",
      "skills": [
        "cross-entropy",
        "classification-thresholds"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 10,
      "prerequisites": [
        "conditional-risk",
        "logarithms"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-classification-advanced-cost-threshold/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-classification-advanced-cost-threshold/"
    },
    {
      "id": "ml-screen-gradient-descent-foundation-updates",
      "title": "Two gradient updates",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "gradient-descent",
      "topic_title": "Gradient Descent",
      "skills": [
        "gradient-update",
        "learning-rate"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "derivatives"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-gradient-descent-foundation-updates/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-gradient-descent-foundation-updates/"
    },
    {
      "id": "ml-screen-gradient-descent-standard-convergence",
      "title": "Learning-rate stability",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "gradient-descent",
      "topic_title": "Gradient Descent",
      "skills": [
        "gradient-update",
        "learning-rate",
        "convergence"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "quadratics",
        "inequalities"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-gradient-descent-standard-convergence/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-gradient-descent-standard-convergence/"
    },
    {
      "id": "ml-screen-gradient-descent-advanced-sgd",
      "title": "SGD unbiasedness and variance",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "gradient-descent",
      "topic_title": "Gradient Descent",
      "skills": [
        "gradient-update",
        "sgd"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 9,
      "prerequisites": [
        "expectation",
        "variance"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-gradient-descent-advanced-sgd/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-gradient-descent-advanced-sgd/"
    },
    {
      "id": "ml-screen-optimization-foundation-stationary",
      "title": "Stationary point and convexity",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "optimization",
      "topic_title": "Optimization",
      "skills": [
        "objective-functions",
        "optimization-stationary-points",
        "optimization-convexity"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "derivatives"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-optimization-foundation-stationary/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-optimization-foundation-stationary/"
    },
    {
      "id": "ml-screen-optimization-standard-l1-l2",
      "title": "Compare L1 and L2 solutions",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "optimization",
      "topic_title": "Optimization",
      "skills": [
        "objective-functions",
        "optimization-stationary-points",
        "optimization-convexity",
        "optimization-regularization"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "subgradients",
        "derivatives"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-optimization-standard-l1-l2/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-optimization-standard-l1-l2/"
    },
    {
      "id": "ml-screen-optimization-advanced-diagnostics",
      "title": "Diagnose optimization traces",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "optimization",
      "topic_title": "Optimization",
      "skills": [
        "objective-functions",
        "optimization-regularization",
        "optimization-diagnostics"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "gradient-norm",
        "hessian",
        "regularized-objectives"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-optimization-advanced-diagnostics/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-optimization-advanced-diagnostics/"
    },
    {
      "id": "ml-screen-neural-networks-foundation-forward",
      "title": "ReLU forward pass",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "neural-networks",
      "topic_title": "Neural Networks",
      "skills": [
        "forward-pass",
        "activations"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "matrix-vector-multiplication",
        "relu"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-neural-networks-foundation-forward/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-neural-networks-foundation-forward/"
    },
    {
      "id": "ml-screen-neural-networks-standard-backprop",
      "title": "Backpropagate through tanh",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "neural-networks",
      "topic_title": "Neural Networks",
      "skills": [
        "forward-pass",
        "activations",
        "neural-network-chain-rule",
        "backpropagation",
        "neural-network-losses"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "chain-rule",
        "tanh-derivative"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-neural-networks-standard-backprop/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-neural-networks-standard-backprop/"
    },
    {
      "id": "ml-screen-neural-networks-advanced-softmax",
      "title": "Parameters and output gradient",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "neural-networks",
      "topic_title": "Neural Networks",
      "skills": [
        "neural-network-chain-rule",
        "backpropagation",
        "neural-network-losses",
        "dense-network-parameter-count"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 10,
      "prerequisites": [
        "softmax-cross-entropy",
        "outer-products"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-neural-networks-advanced-softmax/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-neural-networks-advanced-softmax/"
    },
    {
      "id": "ml-screen-convolution-foundation-operation",
      "title": "Valid convolution output",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "convolution",
      "topic_title": "Convolution",
      "skills": [
        "convolution-operation"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "matrix-arithmetic"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-convolution-foundation-operation/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-convolution-foundation-operation/"
    },
    {
      "id": "ml-screen-convolution-standard-shape",
      "title": "Convolution and pooling geometry",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "convolution",
      "topic_title": "Convolution",
      "skills": [
        "output-shape",
        "padding",
        "stride",
        "convolution-parameter-count",
        "pooling"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "floor-function",
        "tensor-shapes"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-convolution-standard-shape/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-convolution-standard-shape/"
    },
    {
      "id": "ml-screen-convolution-advanced-receptive-field",
      "title": "Receptive field through a stack",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "convolution",
      "topic_title": "Convolution",
      "skills": [
        "output-shape",
        "pooling",
        "receptive-field"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 9,
      "prerequisites": [
        "convolution-output-size",
        "stride"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-convolution-advanced-receptive-field/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-convolution-advanced-receptive-field/"
    },
    {
      "id": "ml-screen-dimensionality-foundation-centering",
      "title": "Center data and find PCA direction",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "dimensionality-reduction",
      "topic_title": "Dimensionality Reduction",
      "skills": [
        "centering",
        "covariance-eigendecomposition",
        "explained-variance"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "means",
        "covariance",
        "eigenvectors"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-dimensionality-foundation-centering/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-dimensionality-foundation-centering/"
    },
    {
      "id": "ml-screen-dimensionality-standard-svd",
      "title": "Connect SVD to PCA",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "dimensionality-reduction",
      "topic_title": "Dimensionality Reduction",
      "skills": [
        "covariance-eigendecomposition",
        "pca-via-svd",
        "explained-variance"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "svd",
        "eigenvalues"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-dimensionality-standard-svd/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-dimensionality-standard-svd/"
    },
    {
      "id": "ml-screen-dimensionality-advanced-objective",
      "title": "Optimal rank-two PCA",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "dimensionality-reduction",
      "topic_title": "Dimensionality Reduction",
      "skills": [
        "pca-objective",
        "covariance-eigendecomposition",
        "explained-variance"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "orthogonal-projection",
        "covariance-eigendecomposition"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-dimensionality-advanced-objective/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-dimensionality-advanced-objective/"
    },
    {
      "id": "ml-screen-unsupervised-foundation-kmeans",
      "title": "One k-means iteration",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "unsupervised-learning",
      "topic_title": "Unsupervised Learning",
      "skills": [
        "k-means",
        "clustering-objective"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "squared-distance",
        "means"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-unsupervised-foundation-kmeans/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-unsupervised-foundation-kmeans/"
    },
    {
      "id": "ml-screen-unsupervised-standard-gmm",
      "title": "GMM responsibilities and M-step",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "unsupervised-learning",
      "topic_title": "Unsupervised Learning",
      "skills": [
        "gaussian-mixtures",
        "expectation-maximization"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 9,
      "prerequisites": [
        "bayes-rule",
        "weighted-means"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-unsupervised-standard-gmm/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-unsupervised-standard-gmm/"
    },
    {
      "id": "ml-screen-unsupervised-advanced-local-optima",
      "title": "Compare k-means fixed points",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "unsupervised-learning",
      "topic_title": "Unsupervised Learning",
      "skills": [
        "k-means",
        "clustering-objective"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 11,
      "prerequisites": [
        "k-means",
        "squared-distance"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-unsupervised-advanced-local-optima/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-unsupervised-advanced-local-optima/"
    },
    {
      "id": "ml-screen-theory-foundation-splits",
      "title": "Train, validation, and test roles",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "theory",
      "topic_title": "Theory",
      "skills": [
        "generalization",
        "train-validation-test"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "supervised-learning-basics"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-theory-foundation-splits/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-theory-foundation-splits/"
    },
    {
      "id": "ml-screen-theory-standard-bias-variance",
      "title": "Compute bias and variance",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "theory",
      "topic_title": "Theory",
      "skills": [
        "bias-variance",
        "generalization"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "expectation",
        "variance",
        "squared-error"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-theory-standard-bias-variance/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-theory-standard-bias-variance/"
    },
    {
      "id": "ml-screen-theory-advanced-complexity",
      "title": "Select model complexity",
      "collection": "screening",
      "area": "machine-learning",
      "area_title": "Machine Learning",
      "topic": "theory",
      "topic_title": "Theory",
      "skills": [
        "bias-variance",
        "generalization",
        "overfitting",
        "train-validation-test",
        "model-complexity"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "error-rates",
        "data-splits"
      ],
      "summary": "Original Screening question.",
      "path": "item/ml-screen-theory-advanced-complexity/",
      "url": "https://mlprep.iwase.dev/item/ml-screen-theory-advanced-complexity/"
    },
    {
      "id": "math-la-01-matrix-invariants",
      "title": "Matrix arithmetic and invariants",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "matrix-operations",
        "inverse",
        "determinant",
        "trace",
        "matrix-norms"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "matrix-arithmetic",
        "square-roots"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-la-01-matrix-invariants/",
      "url": "https://mlprep.iwase.dev/item/math-la-01-matrix-invariants/"
    },
    {
      "id": "math-la-02-system-subspaces",
      "title": "One reduction, four structural conclusions",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "linear-systems",
        "row-reduction",
        "rank",
        "subspaces",
        "rank-nullity"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "linear-combinations",
        "reduced-row-echelon-form"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-la-02-system-subspaces/",
      "url": "https://mlprep.iwase.dev/item/math-la-02-system-subspaces/"
    },
    {
      "id": "math-la-03-basis-coordinates",
      "title": "Detect dependence and use a basis",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "linear-independence",
        "basis-dimension",
        "change-of-basis"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "linear-combinations"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-la-03-basis-coordinates/",
      "url": "https://mlprep.iwase.dev/item/math-la-03-basis-coordinates/"
    },
    {
      "id": "math-la-04-orthogonal-projection",
      "title": "Projection and orthogonal residual",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "orthogonality",
        "projection"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "dot-products"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-la-04-orthogonal-projection/",
      "url": "https://mlprep.iwase.dev/item/math-la-04-orthogonal-projection/"
    },
    {
      "id": "math-la-05-qr-least-squares",
      "title": "Thin QR and a least-squares fit",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "qr",
        "least-squares"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "orthogonality",
        "triangular-systems"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-la-05-qr-least-squares/",
      "url": "https://mlprep.iwase.dev/item/math-la-05-qr-least-squares/"
    },
    {
      "id": "math-la-06-spectral-power",
      "title": "Diagonalize a symmetric matrix",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "eigenvalues",
        "eigenvectors",
        "diagonalization",
        "symmetric-matrices"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "determinants",
        "matrix-multiplication"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-la-06-spectral-power/",
      "url": "https://mlprep.iwase.dev/item/math-la-06-spectral-power/"
    },
    {
      "id": "math-la-07-quadratic-positive",
      "title": "Certify a quadratic form",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "quadratic-forms",
        "positive-definite-semidefinite"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "eigenvalues",
        "unit-vectors"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-la-07-quadratic-positive/",
      "url": "https://mlprep.iwase.dev/item/math-la-07-quadratic-positive/"
    },
    {
      "id": "math-la-08-svd-low-rank-pca",
      "title": "SVD, best rank one, and PCA energy",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "linear-algebra",
      "topic_title": "Linear Algebra",
      "skills": [
        "svd",
        "low-rank-approximation",
        "pca-via-svd"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "orthogonality",
        "matrix-norms",
        "eigenvalues"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-la-08-svd-low-rank-pca/",
      "url": "https://mlprep.iwase.dev/item/math-la-08-svd-low-rank-pca/"
    },
    {
      "id": "math-calc-01-removable-limit",
      "title": "Limit, continuity, derivative, and integral",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "limits",
        "continuity",
        "single-variable-differentiation",
        "single-variable-integration"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "factoring-polynomials",
        "basic-integration"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-calc-01-removable-limit/",
      "url": "https://mlprep.iwase.dev/item/math-calc-01-removable-limit/"
    },
    {
      "id": "math-calc-02-gradient-direction",
      "title": "Gradient and a normalized direction",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "partial-derivatives",
        "gradient",
        "directional-derivative"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "derivatives",
        "dot-products"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-calc-02-gradient-direction/",
      "url": "https://mlprep.iwase.dev/item/math-calc-02-gradient-direction/"
    },
    {
      "id": "math-calc-03-jacobian-chain",
      "title": "Vector chain rule",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "jacobian",
        "multivariable-chain-rule"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "partial-derivatives",
        "matrix-multiplication"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-calc-03-jacobian-chain/",
      "url": "https://mlprep.iwase.dev/item/math-calc-03-jacobian-chain/"
    },
    {
      "id": "math-calc-04-second-order-taylor",
      "title": "A two-variable quadratic approximation",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "taylor-approximation",
        "hessian"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "partial-derivatives",
        "quadratic-forms"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-calc-04-second-order-taylor/",
      "url": "https://mlprep.iwase.dev/item/math-calc-04-second-order-taylor/"
    },
    {
      "id": "math-calc-05-critical-classification",
      "title": "Classify all stationary points",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "calculus-stationary-points",
        "unconstrained-optimization",
        "calculus-convexity"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "gradient",
        "hessian",
        "eigenvalue-sign-test"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-calc-05-critical-classification/",
      "url": "https://mlprep.iwase.dev/item/math-calc-05-critical-classification/"
    },
    {
      "id": "math-calc-06-lagrange-circle",
      "title": "Minimum under an equality constraint",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "constrained-optimization"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "partial-derivatives",
        "linear-equations"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-calc-06-lagrange-circle/",
      "url": "https://mlprep.iwase.dev/item/math-calc-06-lagrange-circle/"
    },
    {
      "id": "math-calc-07-implicit-slope",
      "title": "Implicit tangent slope",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "implicit-differentiation"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "chain-rule",
        "algebra"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-calc-07-implicit-slope/",
      "url": "https://mlprep.iwase.dev/item/math-calc-07-implicit-slope/"
    },
    {
      "id": "math-calc-08-least-squares-derivatives",
      "title": "Matrix derivative with a numeric check",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "calculus",
      "topic_title": "Calculus",
      "skills": [
        "matrix-calculus"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "chain-rule",
        "matrix-multiplication",
        "gradient"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-calc-08-least-squares-derivatives/",
      "url": "https://mlprep.iwase.dev/item/math-calc-08-least-squares-derivatives/"
    },
    {
      "id": "math-prob-01-counting-events",
      "title": "Count a union of selection events",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "counting",
        "event-algebra",
        "inclusion-exclusion"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "combinations",
        "fractions"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-01-counting-events/",
      "url": "https://mlprep.iwase.dev/item/math-prob-01-counting-events/"
    },
    {
      "id": "math-prob-02-bayes-base-rate",
      "title": "Bayes rule with a base rate",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "conditional-probability",
        "total-probability",
        "bayes-rule",
        "probabilistic-independence"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "event-probability",
        "fractions"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-02-bayes-base-rate/",
      "url": "https://mlprep.iwase.dev/item/math-prob-02-bayes-base-rate/"
    },
    {
      "id": "math-prob-03-binomial-moments",
      "title": "A small discrete distribution",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "discrete-random-variables",
        "pmf",
        "named-distributions",
        "expectation",
        "variance"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "binomial-coefficients"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-03-binomial-moments/",
      "url": "https://mlprep.iwase.dev/item/math-prob-03-binomial-moments/"
    },
    {
      "id": "math-prob-04-exponential-transform",
      "title": "Transform an exponential variable",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "continuous-random-variables",
        "pdf",
        "cdf",
        "transformations",
        "named-distributions"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "cumulative-distribution-functions",
        "exponential-distribution"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-04-exponential-transform/",
      "url": "https://mlprep.iwase.dev/item/math-prob-04-exponential-transform/"
    },
    {
      "id": "math-prob-05-joint-correlation",
      "title": "Read dependence from a joint table",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "joint-distributions",
        "marginal-distributions",
        "conditional-distributions",
        "covariance",
        "correlation"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "conditional-probability",
        "expectation",
        "variance"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-05-joint-correlation/",
      "url": "https://mlprep.iwase.dev/item/math-prob-05-joint-correlation/"
    },
    {
      "id": "math-prob-06-total-variance",
      "title": "Condition first, then remove conditioning",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "conditional-expectation",
        "law-total-expectation",
        "law-total-variance"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "conditional-probability",
        "expectation",
        "variance"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-06-total-variance/",
      "url": "https://mlprep.iwase.dev/item/math-prob-06-total-variance/"
    },
    {
      "id": "math-prob-07-sum-clt",
      "title": "Approximate a binomial central range",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "sums-of-random-variables",
        "central-limit-theorem"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "bernoulli-distribution",
        "normal-standardization"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-07-sum-clt/",
      "url": "https://mlprep.iwase.dev/item/math-prob-07-sum-clt/"
    },
    {
      "id": "math-prob-08-lln-interpretation",
      "title": "State the LLN operationally",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "law-of-large-numbers"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 2,
      "prerequisites": [
        "sample-means",
        "convergence-in-probability"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-08-lln-interpretation/",
      "url": "https://mlprep.iwase.dev/item/math-prob-08-lln-interpretation/"
    },
    {
      "id": "math-prob-09-gaussian-linear-map",
      "title": "Linear image of a multivariate Gaussian",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "probability",
      "topic_title": "Probability",
      "skills": [
        "multivariate-gaussian",
        "transformations",
        "covariance"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "matrix-multiplication",
        "gaussian-distribution"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-prob-09-gaussian-linear-map/",
      "url": "https://mlprep.iwase.dev/item/math-prob-09-gaussian-linear-map/"
    },
    {
      "id": "math-stats-01-sample-mean",
      "title": "Sampling distribution and standard error",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "samples",
        "sample-statistics",
        "sampling-distributions",
        "standard-error"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "normal-distribution",
        "sample-mean"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-01-sample-mean/",
      "url": "https://mlprep.iwase.dev/item/math-stats-01-sample-mean/"
    },
    {
      "id": "math-stats-02-shrunken-proportion",
      "title": "Bias, variance, MSE, and consistency",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "estimator-bias",
        "estimator-variance",
        "mean-squared-error",
        "consistency"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "expectation",
        "variance",
        "bernoulli-distribution"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-02-shrunken-proportion/",
      "url": "https://mlprep.iwase.dev/item/math-stats-02-shrunken-proportion/"
    },
    {
      "id": "math-stats-03-exponential-mle",
      "title": "Build and maximize a likelihood",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "likelihood",
        "maximum-likelihood"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "exponential-distribution",
        "logarithms",
        "derivatives"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-03-exponential-mle/",
      "url": "https://mlprep.iwase.dev/item/math-stats-03-exponential-mle/"
    },
    {
      "id": "math-stats-04-beta-posterior-map",
      "title": "Conjugate update and MAP",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "map",
        "bayesian-updating"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "bernoulli-likelihood",
        "beta-distribution"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-04-beta-posterior-map/",
      "url": "https://mlprep.iwase.dev/item/math-stats-04-beta-posterior-map/"
    },
    {
      "id": "math-stats-05-uniform-mom",
      "title": "Method of moments for an endpoint",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "method-of-moments"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 2,
      "prerequisites": [
        "sample-mean",
        "uniform-distribution"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-05-uniform-mom/",
      "url": "https://mlprep.iwase.dev/item/math-stats-05-uniform-mom/"
    },
    {
      "id": "math-stats-06-z-confidence-interval",
      "title": "Confidence interval with known variance",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "confidence-intervals"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 3,
      "prerequisites": [
        "standard-error",
        "normal-quantiles"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-06-z-confidence-interval/",
      "url": "https://mlprep.iwase.dev/item/math-stats-06-z-confidence-interval/"
    },
    {
      "id": "math-stats-07-one-sided-z-test",
      "title": "Hypotheses, critical region, and p-value",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "null-alternative",
        "p-values",
        "critical-regions"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 4,
      "prerequisites": [
        "sampling-distributions",
        "standard-error"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-07-one-sided-z-test/",
      "url": "https://mlprep.iwase.dev/item/math-stats-07-one-sided-z-test/"
    },
    {
      "id": "math-stats-08-power-of-z-test",
      "title": "Type II error and power at an alternative",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "type-i-error",
        "type-ii-error",
        "statistical-power"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "null-alternative",
        "normal-standardization"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-08-power-of-z-test/",
      "url": "https://mlprep.iwase.dev/item/math-stats-08-power-of-z-test/"
    },
    {
      "id": "math-stats-09-chi-square-fit",
      "title": "Chi-square goodness of fit",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "goodness-of-fit",
        "chi-square"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "hypothesis-tests",
        "expected-counts"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-09-chi-square-fit/",
      "url": "https://mlprep.iwase.dev/item/math-stats-09-chi-square-fit/"
    },
    {
      "id": "math-stats-10-simple-regression",
      "title": "Fit a simple regression line",
      "collection": "screening",
      "area": "mathematics",
      "area_title": "Mathematics",
      "topic": "statistics",
      "topic_title": "Statistics",
      "skills": [
        "simple-linear-regression"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "sample-means",
        "algebra"
      ],
      "summary": "Original Screening question.",
      "path": "item/math-stats-10-simple-regression/",
      "url": "https://mlprep.iwase.dev/item/math-stats-10-simple-regression/"
    },
    {
      "id": "prog-cf-trace-sentinel",
      "title": "Trace a sentinel-based string scan",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "control-flow",
      "topic_title": "Control Flow",
      "skills": [
        "conditionals",
        "loops",
        "strings"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 5,
      "prerequisites": [
        "string iteration",
        "character predicates"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-cf-trace-sentinel/",
      "url": "https://mlprep.iwase.dev/item/prog-cf-trace-sentinel/"
    },
    {
      "id": "prog-cf-summarize-runs",
      "title": "Summarize consecutive character runs",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "control-flow",
      "topic_title": "Control Flow",
      "skills": [
        "conditionals",
        "loops",
        "strings"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 10,
      "prerequisites": [
        "string indexing",
        "list append"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-cf-summarize-runs/",
      "url": "https://mlprep.iwase.dev/item/prog-cf-summarize-runs/"
    },
    {
      "id": "prog-cf-split-top-level",
      "title": "Split only at top-level commas",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "control-flow",
      "topic_title": "Control Flow",
      "skills": [
        "conditionals",
        "loops",
        "strings"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 14,
      "prerequisites": [
        "string traversal",
        "loop invariants"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-cf-split-top-level/",
      "url": "https://mlprep.iwase.dev/item/prog-cf-split-top-level/"
    },
    {
      "id": "prog-ds-container-plan",
      "title": "Choose a built-in container by operation",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "sequence-data-structures",
        "dictionaries",
        "sets",
        "stack",
        "queue",
        "heap",
        "hash-map"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 7,
      "prerequisites": [
        "Python built-in containers"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-ds-container-plan/",
      "url": "https://mlprep.iwase.dev/item/prog-ds-container-plan/"
    },
    {
      "id": "prog-ds-postfix-stack",
      "title": "Evaluate postfix arithmetic with a stack",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "stack"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 12,
      "prerequisites": [
        "integer parsing",
        "valid postfix notation"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-ds-postfix-stack/",
      "url": "https://mlprep.iwase.dev/item/prog-ds-postfix-stack/"
    },
    {
      "id": "prog-ds-first-binary-search",
      "title": "Find the first matching index by binary search",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "binary-search",
        "sequence-data-structures"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 12,
      "prerequisites": [
        "sorted lists",
        "half-open intervals"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-ds-first-binary-search/",
      "url": "https://mlprep.iwase.dev/item/prog-ds-first-binary-search/"
    },
    {
      "id": "prog-ds-bfs-distances",
      "title": "Compute unweighted distances with BFS",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "queue",
        "bfs",
        "dictionaries",
        "hash-map"
      ],
      "priority": "stretch",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 18,
      "prerequisites": [
        "adjacency lists",
        "graph reachability"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-ds-bfs-distances/",
      "url": "https://mlprep.iwase.dev/item/prog-ds-bfs-distances/"
    },
    {
      "id": "prog-ds-iterative-dfs",
      "title": "Traverse reachable nodes with iterative DFS",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "dfs",
        "stack",
        "dictionaries",
        "sets"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 15,
      "prerequisites": [
        "adjacency lists",
        "stack operations"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-ds-iterative-dfs/",
      "url": "https://mlprep.iwase.dev/item/prog-ds-iterative-dfs/"
    },
    {
      "id": "prog-ds-merge-sorted-lists",
      "title": "Merge sorted lists with a heap",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "data-structures",
      "topic_title": "Data Structures",
      "skills": [
        "heap",
        "sequence-data-structures"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 18,
      "prerequisites": [
        "sorted lists",
        "heap push and pop"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-ds-merge-sorted-lists/",
      "url": "https://mlprep.iwase.dev/item/prog-ds-merge-sorted-lists/"
    },
    {
      "id": "prog-py-alias-copy-equality",
      "title": "Trace aliasing, shallow copy, and equality",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "python",
      "topic_title": "Python",
      "skills": [
        "python-sequence-semantics",
        "mutability",
        "aliasing",
        "shallow-copy",
        "value-equality"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "nested lists",
        "object identity"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-py-alias-copy-equality/",
      "url": "https://mlprep.iwase.dev/item/prog-py-alias-copy-equality/"
    },
    {
      "id": "prog-py-mutable-default",
      "title": "Diagnose a mutable default argument",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "python",
      "topic_title": "Python",
      "skills": [
        "python-syntax",
        "functions",
        "mutability",
        "aliasing"
      ],
      "priority": "foundation",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "function parameters",
        "list mutation"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-py-mutable-default/",
      "url": "https://mlprep.iwase.dev/item/prog-py-mutable-default/"
    },
    {
      "id": "prog-py-list-complexity",
      "title": "Reason about list-operation complexity",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "python",
      "topic_title": "Python",
      "skills": [
        "complexity",
        "python-syntax",
        "functions",
        "python-sequence-semantics"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 8,
      "prerequisites": [
        "list membership",
        "list count",
        "asymptotic notation"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-py-list-complexity/",
      "url": "https://mlprep.iwase.dev/item/prog-py-list-complexity/"
    },
    {
      "id": "prog-py-point-equality",
      "title": "Implement value equality for a mutable class",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "python",
      "topic_title": "Python",
      "skills": [
        "classes",
        "value-equality",
        "mutability",
        "aliasing"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 15,
      "prerequisites": [
        "methods",
        "object identity",
        "NotImplemented"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-py-point-equality/",
      "url": "https://mlprep.iwase.dev/item/prog-py-point-equality/"
    },
    {
      "id": "prog-rec-digit-sum-trace",
      "title": "Trace recursive calls and returns",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "recursion",
      "topic_title": "Recursion",
      "skills": [
        "base-case",
        "recursive-trace"
      ],
      "priority": "foundation",
      "difficulty": "easy",
      "origin": "original",
      "estimated_minutes": 6,
      "prerequisites": [
        "integer division",
        "remainder",
        "call stack"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-rec-digit-sum-trace/",
      "url": "https://mlprep.iwase.dev/item/prog-rec-digit-sum-trace/"
    },
    {
      "id": "prog-rec-palindrome-indices",
      "title": "Check a palindrome recursively by indices",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "recursion",
      "topic_title": "Recursion",
      "skills": [
        "base-case",
        "recursive-implementation"
      ],
      "priority": "core",
      "difficulty": "medium",
      "origin": "original",
      "estimated_minutes": 10,
      "prerequisites": [
        "string indexing",
        "recursive call stack"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-rec-palindrome-indices/",
      "url": "https://mlprep.iwase.dev/item/prog-rec-palindrome-indices/"
    },
    {
      "id": "prog-rec-nested-total",
      "title": "Sum an arbitrarily nested integer list",
      "collection": "screening",
      "area": "programming",
      "area_title": "Programming",
      "topic": "recursion",
      "topic_title": "Recursion",
      "skills": [
        "base-case",
        "recursive-implementation"
      ],
      "priority": "stretch",
      "difficulty": "hard",
      "origin": "original",
      "estimated_minutes": 15,
      "prerequisites": [
        "type checks",
        "recursive decomposition"
      ],
      "summary": "Original Screening question.",
      "path": "item/prog-rec-nested-total/",
      "url": "https://mlprep.iwase.dev/item/prog-rec-nested-total/"
    }
  ]
}