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Alkis Kalavasis

17 accepted papers

2026

Linear Regression with Unknown Truncation Beyond Gaussian Features

ICML 2026poster

In truncated linear regression, samples $(x,y)$ are shown only when the outcome $y$ falls inside a certain survival set $S^\star$ and the goal is to estimate the unknown $d$-dimensional regressor $w^\star$. This problem has a long history of study in Statistics and Machine Learning going back to the…

Cited by 0SourceScholar
2026

Mean Estimation from Coarse Data: Characterizations and Efficient Algorithms

ICLR 2026poster

Coarse data arise when learners observe only partial information about samples; namely, a set containing the sample rather than its exact value. This occurs naturally through measurement rounding, sensor limitations, and lag in economic systems. We study Gaussian mean estimation from coarse data, wh…

Cited by 0SourceScholar
2025

Does Generation Require Memorization? Creative Diffusion Models using Ambient Diffusion

ICML 2025poster

There is strong empirical evidence that the stateof-the-art diffusion modeling paradigm leads to models that memorize the training set, especially when the training set is small. Prior methods to mitigate the memorization problem often lead to decrease in image quality. Is it possible to obtain stro…

Cited by 0SourcePDFScholar
2024

Injecting Undetectable Backdoors in Obfuscated Neural Networks and Language Models

NeurIPS 2024poster

As ML models become increasingly complex and integral to high-stakes domains such as finance and healthcare, they also become more susceptible to sophisticated adversarial attacks. We investigate the threat posed by undetectable backdoors, as defined in Goldwasser et al. [2022], in models developed…

Cited by 1SourcePDFScholar
2024

On the Computational Landscape of Replicable Learning

NeurIPS 2024poster

We study computational aspects of algorithmic replicability, a notion of stability introduced by Impagliazzo, Lei, Pitassi, and Sorrell [STOC, 2022]. Motivated by a recent line of work that established strong statistical connections between replicability and other notions of learnability such as onl…

Cited by 3SourcePDFScholar
2024

Replicable Learning of Large-Margin Halfspaces

ICML 2024spotlight

We provide an efficient replicable algorithm for the problem of learning large-margin halfspaces. Our results improve upon the algorithms provided by Impagliazzo, Lei, Pitassi, and Sorrell (STOC, 2022). We design the first dimension-independent replicable algorithm for this task which runs in polyno…

Cited by 10SourcePDFScholar
2023

Optimal Learners for Realizable Regression: PAC Learning and Online Learning

NeurIPS 2023oral

In this work, we aim to characterize the statistical complexity of realizable regression both in the PAC learning setting and the online learning setting. Previous work had established the sufficiency of finiteness of the fat shattering dimension for PAC learnability and the necessity of finiteness…

Cited by 27SourcePDFScholar
2023

Optimizing Solution-Samplers for Combinatorial Problems: The Landscape of Policy-Gradient Method

NeurIPS 2023oral

Deep Neural Networks and Reinforcement Learning methods have empirically shown great promise in tackling challenging combinatorial problems. In those methods a deep neural network is used as a solution generator which is then trained by gradient-based methods (e.g., policy gradient) to successively…

Cited by 8SourcePDFScholar
2023

Replicable Bandits

ICLR 2023poster

In this paper, we introduce the notion of replicable policies in the context of stochastic bandits, one of the canonical problems in interactive learning. A policy in the bandit environment is called replicable if it pulls, with high probability, the exact same sequence of arms in two different and…

Cited by 26SourcePDFScholar
2023

Statistical Indistinguishability of Learning Algorithms

ICML 2023poster

When two different parties use the same learning rule on their own data, how can we test whether the distributions of the two outcomes are similar? In this paper, we study the similarity of outcomes of learning rules through the lens of the Total Variation (TV) distance of distributions. We say that…

Cited by 29SourcePDFScholar
2022

Differentially Private Regression with Unbounded Covariates

AISTATS 2022poster

We provide computationally efficient, differentially private algorithms for the classical regression settings of Least Squares Fitting, Binary Regression and Linear Regression with unbounded covariates. Prior to our work, privacy constraints in such regression settings were studied under strong a pr…

Cited by 16SourcePDFScholar
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
2022

Multiclass Learnability Beyond the PAC Framework: Universal Rates and Partial Concept Classes

NeurIPS 2022accept

In this paper we study the problem of multiclass classification with a bounded number of different labels $k$, in the realizable setting. We extend the traditional PAC model to a) distribution-dependent learning rates, and b) learning rates under data-dependent assumptions. First, we consider the un…

Cited by 15SourcePDFScholar