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Konstantinos Stavropoulos

10 accepted papers

2025

Learning Neural Networks with Distribution Shift: Efficiently Certifiable Guarantees

ICLR 2025poster

We give the first provably efficient algorithms for learning neural networks with respect to distribution shift. We work in the Testable Learning with Distribution Shift framework (TDS learning) of Klivans et al. (2024), where the learner receives labeled examples from a training distribution and u…

Cited by 0SourcePDFScholar
2025

The Power of Iterative Filtering for Supervised Learning with (Heavy) Contamination

NeurIPS 2025spotlight

Inspired by recent work on learning with distribution shift, we give a general outlier removal algorithm called *iterative polynomial filtering* and show a number of striking applications for supervised learning with contamination: (1) We show that any function class that can be approximated by low-…

Cited by 0SourceScholar
2024

An Efficient Tester-Learner for Halfspaces

ICLR 2024poster

We give the first efficient algorithm for learning halfspaces in the testable learning model recently defined by Rubinfeld and Vasilyan [2022]. In this model, a learner certifies that the accuracy of its output hypothesis is near optimal whenever the training set passes an associated test, and train…

Cited by 14SourcePDFScholar
2024

Efficient Discrepancy Testing for Learning with Distribution Shift

NeurIPS 2024poster

A fundamental notion of distance between train and test distributions from the field of domain adaptation is discrepancy distance. While in general hard to compute, here we provide the first set of provably efficient algorithms for testing *localized* discrepancy distance, where discrepancy is compu…

Cited by 2SourcePDFScholar
2024

Learning Noisy Halfspaces with a Margin: Massart is No Harder than Random

NeurIPS 2024spotlight

We study the problem of PAC learning $\gamma$-margin halfspaces with Massart noise. We propose a simple proper learning algorithm, the Perspectron, that has sample complexity $\widetilde{O}((\epsilon\gamma)^{-2})$ and achieves classification error at most $\eta+\epsilon$ where $\eta$ is the Massart…

Cited by 1SourcePDFScholar
2024

Tolerant Algorithms for Learning with Arbitrary Covariate Shift

NeurIPS 2024spotlight

We study the problem of learning under arbitrary distribution shift, where the learner is trained on a labeled set from one distribution but evaluated on a different, potentially adversarially generated test distribution. We focus on two frameworks: *PQ learning* [GKKM'20], allowing abstention on ad…

Cited by 4SourcePDFScholar
2023

Agnostically Learning Single-Index Models using Omnipredictors

NeurIPS 2023poster

We give the first result for agnostically learning Single-Index Models (SIMs) with arbitrary monotone and Lipschitz activations. All prior work either held only in the realizable setting or required the activation to be known. Moreover, we only require the marginal to have bounded second moments, wh…

Cited by 15SourcePDFScholar
2023

Tester-Learners for Halfspaces: Universal Algorithms

NeurIPS 2023oral

We give the first tester-learner for halfspaces that succeeds universally over a wide class of structured distributions. Our universal tester-learner runs in fully polynomial time and has the following guarantee: the learner achieves error $O(\mathrm{opt}) + \epsilon$ on any labeled distribution tha…

Cited by 17SourcePDFScholar
2022

Learning and Covering Sums of Independent Random Variables with Unbounded Support

NeurIPS 2022accept

We study the problem of covering and learning sums $X = X_1 + \cdots + X_n$ of independent integer-valued random variables $X_i$ (SIIRVs) with infinite support. De et al. at FOCS 2018, showed that even when the collective support of $X_i$'s is of size $4$, the maximum value of the support necessaril…

Cited by 2SourcePDFScholar