L_p Row Sampling by Lewis Weights
summary
Claims a practical method to sample rows so A' preserves ||Ax||_p for all x by sampling with Lewis weights, shows existence and fast computation, and proves L1 concentration with Rademacher comparison and Khinchin bounds. Algorithms run in input-sparsity time (NNZ(A)+poly(d)); iterative weight computation contracts and converges rapidly for 0<p<4. Output sizes: ~d log d rows for p=1, d log d log log d for 1<p<2, and bounds matching prior lp estimates otherwise.
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chapters (28)
- 0:00Intro
- 1:47DATA
- 2:55SUBSAMPLING MATRICES
- 5:42LINEAR MODEL
- 6:48DISTANCE MINIMIZATION
- 8:18ROW SAMPLING Pick some frescaled rows of A
- 10:57ON GRAPHS
- 13:08PREVIOUS POLY-TIME ALGORITHMS
- 14:52GENERAL MATRICES
- 17:24OUR RESULTS
- 20:13IMPORTANCE SAMPLING
- 22:30MATRIX-CHERNOFF BOUNDS
- 24:52WHAT IS LEVERAGE SCORE
- 26:11ISSUE WITHL
- 28:08WHAT DOES WORK
- 31:19SPLITTING BASED VIEW
- 35:29MATRIX CONCENTRATION
- 37:34SPLITTING ROWS
- 41:03RECURSIVE DEFINITION FOR L
- 43:40SUMMARY
- 44:17COMPUTING LEWIS WEIGHTS
- 45:51FASTER ALGORITHM
- 50:08CONVERGENCE FOR L
- 53:12OVERALL SCHEME
- 55:24PROOFS OF KNOWN RESULTS
- 57:07RADAMACHER PROCESSES
- 58:18TRANSFORMATION
- 58:57EACH ENTRY
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