← Search

Grigorios Chrysos

28 accepted papers

2026

Activation-Free Backbones for Image Recognition: Polynomial Alternatives for Spatial and Channel Mixing

ICML 2026poster

Modern vision backbones treat pointwise activations (e.g., ReLU, GELU) and exponential softmax as essential sources of nonlinearity, but we demonstrate they are not required. We design activation-free polynomial alternatives for three core primitives (MLPs, convolutions, and attention), where Hadama…

Cited by 0SourceScholar
2026

Beyond Neuron-Level Sparsity: Achieving Faithful and Interpretable LLMs with Mixture of Decoders

AAAI 2026technical

As large language models (LLMs) scale, ensuring interpretability and privacy becomes critical. This talk addresses these interconnected challenges with novel approaches to model specialization and safety. First, we tackle the dense, distributed nature of LLM representations by casting Mixture-of-Exp

Cited by 0SourcePDFScholar
2026

Why DDIM Hallucinates More than DDPM: A Theoretical Analysis of Reverse Dynamics

ICML 2026poster

We theoretically study the hallucination phenomena in two canonical diffusion samplers: the stochastic Denoising Diffusion Probabilistic Model (DDPM) and the deterministic Denoising Diffusion Implicit Model (DDIM). We analyze the reverse ODE (DDIM) and SDE (DDPM) for a Gaussian mixture target, provi…

Cited by 0SourceScholar
2025

Certified Robustness Under Bounded Levenshtein Distance

ICLR 2025poster

Text classifiers suffer from small perturbations, that if chosen adversarially, can dramatically change the output of the model. Verification methods can provide robustness certificates against such adversarial perturbations, by computing a sound lower bound on the robust accuracy. Nevertheless, exi…

2025

Everything Everywhere All at Once: LLMs can In-Context Learn Multiple Tasks in Superposition

ICML 2025spotlight

Large Language Models (LLMs) have demonstrated remarkable in-context learning (ICL) capabilities. In this study, we explore a surprising phenomenon related to ICL: LLMs can perform multiple, computationally distinct ICL tasks simultaneously, during a single inference call, a capability we term task…

Cited by 3SourcePDFScholar
2025

Towards Interpretability Without Sacrifice: Faithful Dense Layer Decomposition with Mixture of Decoders

NeurIPS 2025poster

Multilayer perceptrons (MLPs) are an integral part of large language models, yet their dense representations render them difficult to understand, edit, and steer. Recent methods learn interpretable approximations via neuron-level sparsity, yet fail to faithfully reconstruct the original mapping--sig…

Cited by 0SourcecodeScholar
2024

Efficient local linearity regularization to overcome catastrophic overfitting

ICLR 2024poster

Catastrophic overfitting (CO) in single-step adversarial training (AT) results in abrupt drops in the adversarial test accuracy (even down to $0$%). For models trained with multi-step AT, it has been observed that the loss function behaves locally linearly with respect to the input, this is however…

2024

Generalization of Scaled Deep ResNets in the Mean-Field Regime

ICLR 2024spotlight

Despite the widespread empirical success of ResNet, the generalization properties of deep ResNet are rarely explored beyond the lazy training regime. In this work, we investigate scaled ResNet in the limit of infinitely deep and wide neural networks, of which the gradient flow is described by a part…

Cited by 5SourcePDFScholar
2024

Going beyond Compositions, DDPMs Can Produce Zero-Shot Interpolations

ICML 2024poster

Denoising Diffusion Probabilistic Models (DDPMs) exhibit remarkable capabilities in image generation, with studies suggesting that they can generalize by composing latent factors learned from the training data. In this work, we go further and study DDPMs trained on strictly separate subsets of the d…

2024

Learning to Remove Cuts in Integer Linear Programming

ICML 2024poster

Cutting plane methods are a fundamental approach for solving integer linear programs (ILPs). In each iteration of such methods, additional linear constraints (cuts) are introduced to the constraint set with the aim of excluding the previous fractional optimal solution while not affecting the optimal…

2024

MIGS: Multi-Identity Gaussian Splatting via Tensor Decomposition

ECCV 2024oral

"We introduce (Multi-Identity Gaussian Splatting), a novel method that learns a single neural representation for multiple identities, using only monocular videos. Recent 3D Gaussian Splatting (3DGS) approaches for human avatars require per-identity optimization. However, learning a multi-identity re…

2024

Multilinear Mixture of Experts: Scalable Expert Specialization through Factorization

NeurIPS 2024poster

The Mixture of Experts (MoE) paradigm provides a powerful way to decompose dense layers into smaller, modular computations often more amenable to human interpretation, debugging, and editability. However, a major challenge lies in the computational cost of scaling the number of experts high enough t…

2024

REST: Efficient and Accelerated EEG Seizure Analysis through Residual State Updates

ICML 2024poster

EEG-based seizure detection models face challenges in terms of inference speed and memory efficiency, limiting their real-time implementation in clinical devices. This paper introduces a novel graph-based residual state update mechanism (REST) for real-time EEG signal analysis in applications such a…

Cited by 6SourcePDFScholar
2024

Revisiting Character-level Adversarial Attacks for Language Models

ICML 2024poster

Adversarial attacks in Natural Language Processing apply perturbations in the character or token levels. Token-level attacks, gaining prominence for their use of gradient-based methods, are susceptible to altering sentence semantics, leading to invalid adversarial examples. While character-level att…

2024

Robust NAS under adversarial training: benchmark, theory, and beyond

ICLR 2024poster

Recent developments in neural architecture search (NAS) emphasize the significance of considering robust architectures against malicious data. However, there is a notable absence of benchmark evaluations and theoretical guarantees for searching these robust architectures, especially when adversarial…

Cited by 6SourcePDFScholar
2023

Benign Overfitting in Deep Neural Networks under Lazy Training

ICML 2023poster

This paper focuses on over-parameterized deep neural networks (DNNs) with ReLU activation functions and proves that when the data distribution is well-separated, DNNs can achieve Bayes-optimal test error for classification while obtaining (nearly) zero-training error under the lazy training regime.…

Cited by 15SourcePDFScholar
2023

Maximum Independent Set: Self-Training through Dynamic Programming

NeurIPS 2023poster

This work presents a graph neural network (GNN) framework for solving the maximum independent set (MIS) problem, inspired by dynamic programming (DP). Specifically, given a graph, we propose a DP-like recursive algorithm based on GNNs that firstly constructs two smaller sub-graphs, predicts the one…

2023

On the Convergence of Encoder-only Shallow Transformers

NeurIPS 2023poster

In this paper, we aim to build the global convergence theory of encoder-only shallow Transformers under a realistic setting from the perspective of architectures, initialization, and scaling under a finite width regime. The difficulty lies in how to tackle the softmax in self-attention mechanism, th…

Cited by 9SourcePDFScholar
2022

Controlling the Complexity and Lipschitz Constant improves Polynomial Nets

ICLR 2022poster

While the class of Polynomial Nets demonstrates comparable performance to neural networks (NN), it currently has neither theoretical generalization characterization nor robustness guarantees. To this end, we derive new complexity bounds for the set of Coupled CP-Decomposition (CCP) and Nested Couple…

Cited by 14SourcePDFScholar
2022

Extrapolation and Spectral Bias of Neural Nets with Hadamard Product: a Polynomial Net Study

NeurIPS 2022accept

Neural tangent kernel (NTK) is a powerful tool to analyze training dynamics of neural networks and their generalization bounds. The study on NTK has been devoted to typical neural network architectures, but it is incomplete for neural networks with Hadamard products (NNs-Hp), e.g., StyleGAN and poly…

Cited by 13SourcePDFScholar
2022

Generalization Properties of NAS under Activation and Skip Connection Search

NeurIPS 2022accept

Neural Architecture Search (NAS) has fostered the automatic discovery of state-of-the-art neural architectures. Despite the progress achieved with NAS, so far there is little attention to theoretical guarantees on NAS. In this work, we study the generalization properties of NAS under a unifying fram…

Cited by 25SourcePDFScholar
2022

Robustness in deep learning: The good (width), the bad (depth), and the ugly (initialization)

NeurIPS 2022accept

We study the average robustness notion in deep neural networks in (selected) wide and narrow, deep and shallow, as well as lazy and non-lazy training settings. We prove that in the under-parameterized setting, width has a negative effect while it improves robustness in the over-parameterized setting…

Cited by 26SourcePDFScholar
2022

Sound and Complete Verification of Polynomial Networks

NeurIPS 2022accept

Polynomial Networks (PNs) have demonstrated promising performance on face and image recognition recently. However, robustness of PNs is unclear and thus obtaining certificates becomes imperative for enabling their adoption in real-world applications. Existing verification algorithms on ReLU neural n…

2022

The Spectral Bias of Polynomial Neural Networks

ICLR 2022poster

Polynomial neural networks (PNNs) have been recently shown to be particularly effective at image generation and face recognition, where high-frequency information is critical. Previous studies have revealed that neural networks demonstrate a $\text{\it{spectral bias}}$ towards low-frequency function…

Cited by 21SourcePDFScholar
2021

Conditional Generation Using Polynomial Expansions

NeurIPS 2021poster

Generative modeling has evolved to a notable field of machine learning. Deep polynomial neural networks (PNNs) have demonstrated impressive results in unsupervised image generation, where the task is to map an input vector (i.e., noise) to a synthesized image. However, the success of PNNs has not be…

2021

Poly-NL: Linear Complexity Non-Local Layers With 3rd Order Polynomials

ICCV 2021poster

Spatial self-attention layers, in the form of Non-Local blocks, introduce long-range dependencies in Convolutional Neural Networks by computing pairwise similarities among all possible positions. Such pairwise functions underpin the effectiveness of non-local layers, but also determine a complexity…

Cited by 14PDFScholar
2020

Multilinear Latent Conditioning for Generating Unseen Attribute Combinations

ICML 2020poster

Deep generative models rely on their inductive bias to facilitate generalization, especially for problems with high dimensional data, like images. However, empirical studies have shown that variational autoencoders (VAE) and generative adversarial networks (GAN) lack the generalization ability that…

Cited by 17SourcePDFScholar