| Tue, Aug 25 |
Introduction. Data as samples from a distribution. Python/NumPy basics |
Notes |
Practice 1 (Python) |
Syllabus |
| Thu, Aug 27 |
Sampling from distributions: uniform, Gaussian; histograms vs. densities; empirical distribution |
Notes |
Quiz 0 (ungraded) · solutions |
C&O §7.1 |
| Tue, Sep 1 |
Multivariate Gaussians and mixtures, operationally: sampling, mean, covariance |
Notes |
Practice 2 (NumPy + sampling) |
C&O §7.1 |
| Thu, Sep 3 |
Matrices that stretch Gaussians; is the best fit a good model? Mixtures of Gaussians by gradient descent |
Notes |
Quiz 1 · solutions |
C&O §7.1 |
| Tue, Sep 8 |
Maximum likelihood; the two-bin test by hand; sizing the experiment; Sanov's theorem exactly |
Notes |
Practice 3 (Gaussian fit + Sanov) |
C&T §11.1–11.4 |
| Thu, Sep 10 |
Relative entropy for densities; Gibbs’ inequality and maximum likelihood as D-minimization; generative models: mixtures, pushforwards, GANs, diffusion |
Notes |
Quiz 2 · solutions |
C&T Ch. 2; MacKay Ch. 2 |
| Tue, Sep 15 |
From samples to graphs: similarity graphs, random walks, the Markov property, and probability distributions on a graph |
Notes |
Practice 4 (model testing) |
C&O §9.1, §9.1.2, §9.6 (pp. 410–412); Zitkovic Ch. 5 |
| Thu, Sep 17 |
The linear algebra of a random walk: the law moves by matrix multiplication; the lazy walk; invariant measure; eigenvalues and the spectral theorem; the graph Laplacian, connected components, and spectral clustering |
Notes |
Quiz 3 · solutions |
C&O §§5.1–5.3, §9.3, §9.4, §9.6; Zitkovic Ch. 5, 8 |
| Tue, Sep 22 |
Two clusters: why the sign of one Laplacian eigenvector cuts a graph; cuts, the normalized cut and its relaxation; a weak bridge by hand; three species and the limits of a sign; k-means |
Notes |
Practice 5 (graphs and the Markov property) |
C&O §9.3, §9.4, §9.7 |
| Thu, Sep 24 |
Reset: from a graph to a vector worth looking at. All the notation on one graph; connected components are not clusters; the spectral theorem, Rayleigh quotient and power method; the identity D−1L = I − P; the power method on the lazy walk and the plateau as the second eigenvector |
Notes |
Quiz 4 · solutions |
C&O §5.3, §9.1, §9.3, §9.6; von Luxburg §§1–3 |
| Tue, Sep 29 |
Eigenvalues without symmetry: diagonalizable matrices and powers; directed graphs and Jordan blocks; the cut problem, its relaxation, and why the answer is an eigenvector; convergence of the lazy walk and relative entropy |
Notes |
Midterm 1 practice |
C&O §5.1, §9.4; Axler Ch. 8 |
| Thu, Oct 1 |
Entropy decay along random walks; eigenvalues set the rate; Google's PageRank; review |
Notes |
Quiz 5 (optional) · solutions |
Zitkovic Ch. 8; C&O §9.6.1 |
| Tue, Oct 6 |
Midterm 1: random walks, linear systems, eigenvector fixed points |
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Midterm 1 · solutions |
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| Thu, Oct 8 |
Coordinates for data and distributions: vector spaces, bases, orthogonality |
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Practice 6 (linear algebra) |
C&O Ch. 1–2 |
| Tue, Oct 13 |
Projections and best approximation of data by a subspace; Gram–Schmidt, QR |
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C&O §2.4–2.5, §4.7 |
| Thu, Oct 15 |
Spectral theorem: covariance matrices of data; reversible chains and reversing a random walk |
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Quiz 6 |
C&O §5.3 |
| Tue, Oct 20 |
Rayleigh quotients: max-variance directions in data; Perron–Frobenius, spectral gap, convergence rate |
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C&O §5.4–5.6 |
| Thu, Oct 22 |
SVD of the data matrix; low-rank approximation |
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Quiz 7 |
C&O §5.7 |
| Thu, Oct 29 |
Lab: k-means clustering hands-on |
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C&O §7.5 |
| Tue, Nov 3 |
Spectral clustering via the graph Laplacian |
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Practice 7 (SVD/eigen) |
C&O §9.4, §9.7.2 |
| Thu, Nov 5 |
PCA via SVD; the covariance matrix |
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Quiz 8 |
C&O §8.1 |
| Tue, Nov 10 |
PCA compression; best approximating subspace |
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Practice 8 (PCA) |
C&O §8.2–8.3 |
| Thu, Nov 12 |
The multivariate Gaussian, formally: affine image of N(0, I); sampling via Σ1/2 |
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Quiz 9; Midterm 2 practice |
C&O §7.1 |
| Tue, Nov 17 |
Mixtures of Gaussians: density, latent variables; GMM as soft k-means |
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Practice 9 (Gaussian sampling) |
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| Thu, Nov 19 |
Midterm 2: eigen-theory, spectral theorem, SVD, spectral clustering, PCA |
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| Nov 24 & 26 |
Fall break / Thanksgiving — no classes |
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| Tue, Dec 1 |
Generative models: forward diffusion as a noising Markov chain; reversing the chain; closed-form scores for Gaussian mixtures |
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Final practice |
Lecture notes |
| Thu, Dec 3 |
Review for final |
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| Sat, Dec 12 |
Final Exam, 1:00–3:00 PM (room TBD): cumulative; emphasis on spectral methods, PCA, Gaussians, generative models |
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