TBD
summary
Proposes a statistical IRM scaffold: three concrete conditions—source-preservation, contraction, Bayes-unifies—and proves that with an oracle representation phi a k‑nearest‑neighbor classifier on source samples reaches target Bayes risk; unlabeled target samples rule out representations that fail contraction, while a small amount of labeled target data disambiguates remaining candidates with sample complexity tied to the VC class of pairwise distance tests. For imbalanced classes, uses convex‑hull geometry and extreme‑value theory (Fisher‑Tippett‑Gnedenko) to show subsampling helps for Gumbel vs Weibull tails* because exponential tails push the max‑margin boundary, whereas bounded‑tail cases don’t benefit.
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chapters (21)
- 0:00Introduction
- 0:44Distribution shift in ML theory
- 2:29Practical distribution shift examples
- 5:47Spurious correlations framework
- 7:14Invariant risk minimization and its limitations
- 8:58Building statistical IRM framework
- 12:14Representation learning assumptions
- 16:44IRM assumptions explained
- 19:44Theoretical guarantees with oracle phi
- 22:14Finding phi without oracle
- 24:41Role of unlabeled target data
- 27:14Insufficient source/target data
- 29:01Spurious correlation results summary
- 30:30Imbalanced data distribution shift intro
- 31:54Practitioner approaches to imbalance
- 34:20Max-margin classifier properties
- 36:48Extreme value theory for imbalance
- 38:14Toy example for imbalanced classes
- 40:44Gumbel vs Weibull distributions
- 42:33Conclusion and open questions
- 43:35Q&A
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