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Zaid Harchaoui

34 accepted papers

2026

BroRL: Scaling Reinforcement Learning via Broadened Exploration

ICML 2026poster

Reinforcement Learning with Verifiable Rewards (RLVR) has emerged as a key ingredient for unlocking complex reasoning capabilities in large language models. Recent work ProRL \citep{liu2025prorl} has shown promise in scaling RL by increasing the number of training steps. However, performance plateau…

Cited by 0SourceScholar
2025

Spectral Differential Network Analysis for High-Dimensional Time Series

AISTATS 2025poster

Spectral networks derived from multivariate time series data arise in many domains, from brain science to Earth science. Often, it is of interest to study how these networks change under different conditions. For instance, to better understand epilepsy, it would be interesting to capture the changes…

Cited by 0SourceScholar
2024

Distributionally Robust Optimization with Bias and Variance Reduction

ICLR 2024spotlight

We consider the distributionally robust optimization (DRO) problem, wherein a learner optimizes the worst-case empirical risk achievable by reweighing the observed training examples. We present Prospect, a stochastic gradient-based algorithm that only requires tuning a single learning rate hyperpara…

Cited by 6SourcePDFScholar
2024

Drago: Primal-Dual Coupled Variance Reduction for Faster Distributionally Robust Optimization

NeurIPS 2024poster

We consider the penalized distributionally robust optimization (DRO) problem with a closed, convex uncertainty set, a setting that encompasses learning using $f$-DRO and spectral/$L$-risk minimization. We present Drago, a stochastic primal-dual algorithm which combines cyclic and randomized componen…

Cited by 1SourcePDFScholar
2024

JAMDEC: Unsupervised Authorship Obfuscation using Constrained Decoding over Small Language Models

NAACL 2024long

The permanence of online content combined with the enhanced authorship identification techniques calls for stronger computational methods to protect the identity and privacy of online authorship when needed, e.g., blind reviews for scientific papers, anonymous online reviews, or anonymous interactio…

2024

StyleRemix: Interpretable Authorship Obfuscation via Distillation and Perturbation of Style Elements

EMNLP 2024main

Authorship obfuscation, rewriting a text to intentionally obscure the identity of the author, is important yet challenging. Current methods using large language models (LLMs) lack interpretability and controllability, often ignoring author-specific stylistic features, resulting in less robust perfor…

2024

The Benefits of Balance: From Information Projections to Variance Reduction

NeurIPS 2024poster

Data balancing across multiple modalities and sources appears in various forms in foundation models in machine learning and AI, e.g., in CLIP and DINO. We show that data balancing across modalities and sources actually offers an unsuspected benefit: variance reduction. We present a non-asymptotic st…

Cited by 0SourcePDFScholar
2023

Faith and Fate: Limits of Transformers on Compositionality

NeurIPS 2023spotlight

Transformer large language models (LLMs) have sparked admiration for their exceptional performance on tasks that demand intricate multi-step reasoning. Yet, these models simultaneously show failures on surprisingly trivial problems. This begs the question: Are these errors incidental, or do they si…

2023

Influence Diagnostics under Self-concordance

AISTATS 2023poster

Influence diagnostics such as influence functions and approximate maximum influence perturbations are popular in machine learning and in AI domain applications. Influence diagnostics are powerful statistical tools to identify influential datapoints or subsets of datapoints. We establish finite-sampl…

2023

Stochastic Optimization for Spectral Risk Measures

AISTATS 2023poster

Spectral risk objectives – also called L-risks – allow for learning systems to interpolate between optimizing average-case performance (as in empirical risk minimization) and worst-case performance on a task. We develop LSVRG, a stochastic algorithm to optimize these quantities by characterizing the…

2022

Triangular Flows for Generative Modeling: Statistical Consistency, Smoothness Classes, and Fast Rates

AISTATS 2022poster

Triangular flows, also known as Knöthe-Rosenblatt measure couplings, comprise an important building block of normalizing flow models for generative modeling and density estimation, including popular autoregressive flows such as real-valued non-volume preserving transformation models (Real NVP). We p…

2021

Divergence Frontiers for Generative Models: Sample Complexity, Quantization Effects, and Frontier Integrals

NeurIPS 2021poster

The spectacular success of deep generative models calls for quantitative tools to measure their statistical performance. Divergence frontiers have recently been proposed as an evaluation framework for generative models, due to their ability to measure the quality-diversity trade-off inherent to deep…

2021

MAUVE: Measuring the Gap Between Neural Text and Human Text using Divergence Frontiers

NeurIPS 2021oral

As major progress is made in open-ended text generation, measuring how close machine-generated text is to human language remains a critical open problem. We introduce Mauve, a comparison measure for open-ended text generation, which directly compares the learnt distribution from a text generation mo…

Cited by 355SourcePDFScholar
2021

Stochastic optimization under time drift: iterate averaging, step-decay schedules, and high probability guarantees

NeurIPS 2021poster

We consider the problem of minimizing a convex function that is evolving in time according to unknown and possibly stochastic dynamics. Such problems abound in the machine learning and signal processing literature, under the names of concept drift and stochastic tracking. We provide novel non-asympt…

Cited by 24SourcePDFScholar
2019

A Statistical Investigation of Long Memory in Language and Music

ICML 2019oral

Representation and learning of long-range dependencies is a central challenge confronted in modern applications of machine learning to sequence data. Yet despite the prominence of this issue, the basic problem of measuring long-range dependence, either in a given data source or as represented in a t…

2019

Iterative Linearized Control: Stable Algorithms and Complexity Guarantees

ICML 2019oral

We examine popular gradient-based algorithms for nonlinear control in the light of the modern complexity analysis of first-order optimization algorithms. The examination reveals that the complexity bounds can be clearly stated in terms of calls to a computational oracle related to dynamic programmin…

Cited by 27SourcePDFScholar
2018

A Smoother Way to Train Structured Prediction Models

NeurIPS 2018poster

We present a framework to train a structured prediction model by performing smoothing on the inference algorithm it builds upon. Smoothing overcomes the non-smoothness inherent to the maximum margin structured prediction objective, and paves the way for the use of fast primal gradient-based optimiza…

2018

Catalyst for Gradient-based Nonconvex Optimization

AISTATS 2018poster

We introduce a generic scheme to solve nonconvex optimization problems using gradient-based algorithms originally designed for minimizing convex functions. Even though these methods may originally require convexity to operate, the proposed approach allows one to use them without assuming any knowled…

Cited by 0SourcePDFScholar
2016

Structure-Blind Signal Recovery

NeurIPS 2016poster

We consider the problem of recovering a signal observed in Gaussian noise. If the set of signals is convex and compact, and can be specified beforehand, one can use classical linear estimators that achieve a risk within a constant factor of the minimax risk. However, when the set is unspecified, des…

2015

EpicFlow: Edge-Preserving Interpolation of Correspondences for Optical Flow

CVPR 2015poster

We propose a novel approach for optical flow estimation, targeted at large displacements with significant occlusions. It consists of two steps: i) dense matching by edge-preserving interpolation from a sparse set of matches; ii) variational energy minimization initialized with the dense matches. The…

2015

Learning to Detect Motion Boundaries

CVPR 2015poster

We propose a learning-based approach for motion boundary detection. Precise localization of motion boundaries is essential for the success of optical flow estimation, as motion boundaries correspond to discontinuities of the optical flow field. The proposed approach allows to predict motion boundari…

2015

Local Convolutional Features With Unsupervised Training for Image Retrieval

ICCV 2015poster

Patch-level descriptors underlie several important computer vision tasks, such as stereo-matching or content-based image retrieval. We introduce a deep convolutional architecture that yields patch-level descriptors, as an alternative to the popular SIFT descriptor for image retrieval. The propo…

Cited by 219PDFScholar