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Ioannis Mitliagkas

38 accepted papers

2026

A Derandomization Framework for Structure Discovery: Applications in Neural Networks and Beyond

ICLR 2026poster

Understanding the dynamics of feature learning in neural networks (NNs) remains a significant challenge. The work of (Mousavi-Hosseini et al., 2023) analyzes a multiple index teacher-student setting and shows that a two-layer student attains a low-rank structure in its first-layer weights when tra…

Cited by 0SourceScholar
2026

Adaptive Batch Sizes Using Non-Euclidean Gradient Noise Scales for Stochastic Sign and Spectral Descent

ICML 2026poster

To maximize hardware utilization, modern machine learning systems typically employ large constant or manually tuned batch size schedules, relying on heuristics that are brittle and costly to tune. Existing adaptive strategies based on gradient noise scale (GNS) offer a principled alternative. Howeve…

Cited by 0SourceScholar
2026

Beyond Multi-Token Prediction: Pretraining LLMs with Future Summaries

ICLR 2026poster

Next-token prediction (NTP) has driven the success of large language models (LLMs), but it struggles with long-horizon reasoning, planning, and creative writing, with these limitations largely attributed to teacher-forced training. Multi-token prediction (MTP) partially mitigates these issues by pre…

Cited by 0SourceScholar
2026

DisTaC: Conditioning Task Vectors via Distillation for Robust Model Merging

ICLR 2026poster

Model merging has emerged as an efficient and flexible paradigm for multi-task learning, with numerous methods being proposed in recent years. However, these state-of-the-art techniques are typically evaluated on benchmark suites that are highly favorable to model merging, and their robustness in m…

Cited by 0SourcecodeScholar
2026

Unlearning with Asymmetric Sources: Improved Unlearning-Utility Trade-off with Public Data

ICML 2026poster

Noise-based certified machine unlearning currently faces a hard ceiling: the noise magnitude required to certify unlearning typically destroys model utility, particularly for large-scale deletion requests. While leveraging public data is a standard technique in differential privacy to relax this ten…

Cited by 0SourceScholar
2025

Compositional Risk Minimization

ICML 2025poster

Compositional generalization is a crucial step towards developing data-efficient intelligent machines that generalize in human-like ways. In this work, we tackle a challenging form of distribution shift, termed compositional shift, where some attribute combinations are completely absent at training…

Cited by 3SourcePDFScholar
2025

Solving hidden monotone variational inequalities with surrogate losses

ICLR 2025poster

Deep learning has proven to be effective in a wide variety of loss minimization problems. However, many applications of interest, like minimizing projected Bellman error and min-max optimization, cannot be modelled as minimizing a scalar loss function but instead correspond to solving a variational…

Cited by 1SourcePDFScholar
2025

Understanding Adam Requires Better Rotation Dependent Assumptions

NeurIPS 2025poster

Despite its widespread adoption, Adam's advantage over Stochastic Gradient Descent (SGD) lacks a comprehensive theoretical explanation. This paper investigates Adam's sensitivity to rotations of the parameter space. We observe that Adam's performance in training transformers degrades under random ro…

Cited by 0SourceScholar
2024

Empirical Analysis of Model Selection for Heterogeneous Causal Effect Estimation

ICLR 2024spotlight

We study the problem of model selection in causal inference, specifically for conditional average treatment effect (CATE) estimation. Unlike machine learning, there is no perfect analogue of cross-validation for model selection as we do not observe the counterfactual potential outcomes. Towards this…

2024

Expecting The Unexpected: Towards Broad Out-Of-Distribution Detection

NeurIPS 2024poster

Deployed machine learning systems require some mechanism to detect out-of-distribution (OOD) inputs. Existing research mainly focuses on one type of distribution shift: detecting samples from novel classes, absent from the training set. However, real-world systems encounter a broad variety of anomal…

2024

No Wrong Turns: The Simple Geometry Of Neural Networks Optimization Paths

ICML 2024poster

Understanding the optimization dynamics of neural networks is necessary for closing the gap between theory and practice. Stochastic first-order optimization algorithms are known to efficiently locate favorable minima in deep neural networks. This efficiency, however, contrasts with the non-convex an…

2023

A Unified Approach to Reinforcement Learning, Quantal Response Equilibria, and Two-Player Zero-Sum Games

ICLR 2023poster

This work studies an algorithm, which we call magnetic mirror descent, that is inspired by mirror descent and the non-Euclidean proximal gradient algorithm. Our contribution is demonstrating the virtues of magnetic mirror descent as both an equilibrium solver and as an approach to reinforcement lear…

2023

Additive Decoders for Latent Variables Identification and Cartesian-Product Extrapolation

NeurIPS 2023oral

We tackle the problems of latent variables identification and "out-of-support'' image generation in representation learning. We show that both are possible for a class of decoders that we call additive, which are reminiscent of decoders used for object-centric representation learning (OCRL) and well…

2023

CADet: Fully Self-Supervised Out-Of-Distribution Detection With Contrastive Learning

NeurIPS 2023poster

Handling out-of-distribution (OOD) samples has become a major stake in the real-world deployment of machine learning systems. This work explores the use of self-supervised contrastive learning to the simultaneous detection of two types of OOD samples: unseen classes and adversarial perturbations. Fi…

2023

Neural Networks Efficiently Learn Low-Dimensional Representations with SGD

ICLR 2023top-25%

We study the problem of training a two-layer neural network (NN) of arbitrary width using stochastic gradient descent (SGD) where the input $\boldsymbol{x}\in \mathbb{R}^d$ is Gaussian and the target $y \in \mathbb{R}$ follows a multiple-index model, i.e., $y=g(\langle\boldsymbol{u_1},\boldsymbol{x}…

Cited by 71SourcePDFScholar
2023

Synergies between Disentanglement and Sparsity: Generalization and Identifiability in Multi-Task Learning

ICML 2023poster

Although disentangled representations are often said to be beneficial for downstream tasks, current empirical and theoretical understanding is limited. In this work, we provide evidence that disentangled representations coupled with sparse task-specific predictors improve generalization. In the cont…

2022

Gradient Descent Is Optimal Under Lower Restricted Secant Inequality And Upper Error Bound

NeurIPS 2022accept

The study of first-order optimization is sensitive to the assumptions made on the objective functions. These assumptions induce complexity classes which play a key role in worst-case analysis, including the fundamental concept of algorithm optimality. Recent work argues that strong convexity and smo…

Cited by 18SourcePDFScholar
2021

A Study of Condition Numbers for First-Order Optimization

AISTATS 2021poster

In this work we introduce a new framework for the theoretical study of convergence and tuning of first-order optimization algorithms (FOA). The study of such algorithms typically requires assumptions on the objective functions: the most popular ones are probably smoothness and strong convexity. Thes…

Cited by 24SourcePDFScholar
2021

Adversarial score matching and improved sampling for image generation

ICLR 2021poster

Denoising Score Matching with Annealed Langevin Sampling (DSM-ALS) has recently found success in generative modeling. The approach works by first training a neural network to estimate the score of a distribution, and then using Langevin dynamics to sample from the data distribution assumed by the sc…

2021

Invariance Principle Meets Information Bottleneck for Out-of-Distribution Generalization

NeurIPS 2021spotlight

The invariance principle from causality is at the heart of notable approaches such as invariant risk minimization (IRM) that seek to address out-of-distribution (OOD) generalization failures. Despite the promising theory, invariance principle-based approaches fail in common classification tasks, whe…

Cited by 313SourcePDFScholar
2021

Stochastic Gradient Descent-Ascent and Consensus Optimization for Smooth Games: Convergence Analysis under Expected Co-coercivity

NeurIPS 2021poster

Two of the most prominent algorithms for solving unconstrained smooth games are the classical stochastic gradient descent-ascent (SGDA) and the recently introduced stochastic consensus optimization (SCO) [Mescheder et al., 2017]. SGDA is known to converge to a stationary point for specific classes o…

2020

A Tight and Unified Analysis of Gradient-Based Methods for a Whole Spectrum of Differentiable Games

AISTATS 2020poster

We consider differentiable games where the goal is to find a Nash equilibrium. The machine learning community has recently started using variants of the gradient method (GD). Prime examples are extragradient (EG), the optimistic gradient method (OG) and consensus optimization (CO) which enjoy linear…

Cited by 117SourcePDFScholar
2020

Accelerating Smooth Games by Manipulating Spectral Shapes

AISTATS 2020poster

We use matrix iteration theory to characterize acceleration in smooth games. We define the spectral shape of a family of games as the set containing all eigenvalues of the Jacobians of standard gradient dynamics in the family. Shapes restricted to the real line represent well-understood classes of p…

Cited by 61SourcePDFScholar
2020

In search of robust measures of generalization

NeurIPS 2020poster

One of the principal scientific challenges in deep learning is explaining generalization, i.e., why the particular way the community now trains networks to achieve small training error also leads to small error on held-out data from the same population. It is widely appreciated that some worst-case…

2020

Linear Lower Bounds and Conditioning of Differentiable Games

ICML 2020poster

Recent successes of game-theoretic formulations in ML have caused a resurgence of research interest in differentiable games. Overwhelmingly, that research focuses on methods and upper bounds on their speed of convergence. In this work, we approach the question of fundamental iteration complexity by…

Cited by 68SourcePDFScholar
2020

Stochastic Hamiltonian Gradient Methods for Smooth Games

ICML 2020poster

The success of adversarial formulations in machine learning has brought renewed motivation for smooth games. In this work, we focus on the class of stochastic Hamiltonian methods and provide the first convergence guarantees for certain classes of stochastic smooth games. We propose a novel unbiased…

Cited by 59SourcePDFScholar
2019

Manifold Mixup: Better Representations by Interpolating Hidden States

ICML 2019oral

Deep neural networks excel at learning the training data, but often provide incorrect and confident predictions when evaluated on slightly different test examples. This includes distribution shifts, outliers, and adversarial examples. To address these issues, we propose \manifoldmixup{}, a simple re…

2019

Multi-objective training of Generative Adversarial Networks with multiple discriminators

ICML 2019oral

Recent literature has demonstrated promising results for training Generative Adversarial Networks by employing a set of discriminators, in contrast to the traditional game involving one generator against a single adversary. Such methods perform single-objective optimization on some simple consolidat…

Cited by 89SourcePDFScholar
2019

Negative Momentum for Improved Game Dynamics

AISTATS 2019poster

Games generalize the single-objective optimization paradigm by introducing different objective functions for different players. Differentiable games often proceed by simultaneous or alternating gradient updates. In machine learning, games are gaining new importance through formulations like generati…

2019

Reducing the variance in online optimization by transporting past gradients

NeurIPS 2019spotlight

Most stochastic optimization methods use gradients once before discarding them. While variance reduction methods have shown that reusing past gradients can be beneficial when there is a finite number of datapoints, they do not easily extend to the online setting. One issue is the staleness due to us…

2019

State-Reification Networks: Improving Generalization by Modeling the Distribution of Hidden Representations

ICML 2019oral

Machine learning promises methods that generalize well from finite labeled data. However, the brittleness of existing neural net approaches is revealed by notable failures, such as the existence of adversarial examples that are misclassified despite being nearly identical to a training example, or t…

Cited by 6SourcePDFScholar
2019

h-detach: Modifying the LSTM Gradient Towards Better Optimization

ICLR 2019poster

Recurrent neural networks are known for their notorious exploding and vanishing gradient problem (EVGP). This problem becomes more evident in tasks where the information needed to correctly solve them exist over long time scales, because EVGP prevents important gradient components from being back-pr…

2018

Learning Representations and Generative Models for 3D Point Clouds

ICLR 2018workshop

Three-dimensional geometric data offer an excellent domain for studying representation learning and generative modeling. In this paper, we look at geometric data represented as point clouds. We introduce a deep autoencoder (AE) network with excellent reconstruction quality and generalization ability…

Cited by 1765SourceScholar
2018

Learning Representations and Generative Models for 3D Point Clouds

ICML 2018oral

Three-dimensional geometric data offer an excellent domain for studying representation learning and generative modeling. In this paper, we look at geometric data represented as point clouds. We introduce a deep AutoEncoder (AE) network with state-of-the-art reconstruction quality and generalization…

2016

Scan Order in Gibbs Sampling: Models in Which it Matters and Bounds on How Much

NeurIPS 2016poster

Gibbs sampling is a Markov Chain Monte Carlo sampling technique that iteratively samples variables from their conditional distributions. There are two common scan orders for the variables: random scan and systematic scan. Due to the benefits of locality in hardware, systematic scan is commonly used,…

Cited by 52SourcePDFScholar