Publications

Sparse Autoencoders Reveal Universal Feature Spaces Across Large Language Models
Michael Lan
Philip Torr
Austin Meek
Ashkan Khakzar
Fazl Barez
Spiral volumetric optoacoustic tomography of reduced oxygen saturation in the spinal cord of M83 mouse model of Parkinson's disease.
Benjamin F. Combes
Sandeep Kumar Kalva
Pierre-Louis Benveniste
Agathe Tournant
Man Hoi Law
Joshua Newton
Maik Krüger
Rebecca Z Weber
Inês Dias
Daniela Noain
Xose Luis Dean-Ben
Uwe Konietzko
Christian R. Baumann
Per-Göran Gillberg
Christoph Hock
Roger M. Nitsch
Daniel Razansky
Ruiqing Ni
Towards Interpreting Visual Information Processing in Vision-Language Models
Clement Neo
Luke Ong
Philip Torr
Mor Geva
Fazl Barez
VCR: Visual Caption Restoration
Tianyu Zhang
Suyuchen Wang
Lu Li
Ge Zhang
Perouz Taslakian
Sai Rajeswar
Jie Fu
We introduce Visual Caption Restoration (VCR), a novel vision-language task that challenges models to accurately restore partially obscured … (see more)texts using pixel-level hints within images. This task stems from the observation that text embedded in images is intrinsically different from common visual elements and natural language due to the need to align the modalities of vision, text, and text embedded in images. While numerous works have integrated text embedded in images into visual question-answering tasks, approaches to these tasks generally rely on optical character recognition or masked language modeling, thus reducing the task to mainly text-based processing. However, text-based processing becomes ineffective in VCR as accurate text restoration depends on the combined information from provided images, context, and subtle cues from the tiny exposed areas of masked texts. We develop a pipeline to generate synthetic images for the VCR task using image-caption pairs, with adjustable caption visibility to control the task difficulty. With this pipeline, we construct a dataset for VCR called VCR-Wiki using images with captions from Wikipedia, comprising 2.11M English and 346K Chinese entities in both easy and hard split variants. Our results reveal that current vision language models significantly lag behind human performance in the VCR task, and merely fine-tuning the models on our dataset does not lead to notable improvements. We release VCR-Wiki and the data construction code to facilitate future research.
VinePPO: Accurate Credit Assignment in RL for LLM Mathematical Reasoning
Amirhossein Kazemnejad
Milad Aghajohari
Eva Portelance
Large language models (LLMs) are increasingly required to solve complex reasoning tasks, like mathematical problems, that involve multiple r… (see more)easoning steps before feedback is received. Effectively identifying and prioritizing key steps by accurately assigning credit to these intermediate steps is essential for enhancing model performance. Proximal Policy Optimization (PPO), a state-of-the-art reinforcement learning algorithm for finetuning LLMs, addresses the credit assignment problem by employing value networks to predict the expected cumulative rewards of intermediate states. In this work, we identify significant limitations with this value estimation method. To address this, we propose \methodname that leverages the flexibility of language environments to compute unbiased Monte Carlo-based estimates of the intermediate values. VinePPO consistently outperforms standard PPO, doing so more efficiently and with lower divergence from the reference model. Our findings underscore the critical importance of accurate credit assignment in LLM post-training and present a simple, yet effective solution.
Compositional Risk Minimization
Divyat Mahajan
Mohammad Pezeshki
Kartik Ahuja
Differentiation Through Black-Box Quadratic Programming Solvers
Connor W. Magoon
Fengyu Yang
Shahar Kovalsky
Path-filtering in path-integral simulations of open quantum systems using GFlowNets
Jeremy Lackman-Mincoff
Moksh J. Jain
Nikolay Malkin
Lena Simine
On the Modeling Capabilities of Large Language Models for Sequential Decision Making
Martin Klissarov
Alexander T Toshev
Bogdan Mazoure
Beyond FVD: Enhanced Evaluation Metrics for Video Generation Quality
Ge Ya Luo
Gian Favero
Zhi Hao Luo
Alexia Jolicoeur-Martineau
The Fr\'echet Video Distance (FVD) is a widely adopted metric for evaluating video generation distribution quality. However, its effectivene… (see more)ss relies on critical assumptions. Our analysis reveals three significant limitations: (1) the non-Gaussianity of the Inflated 3D Convnet (I3D) feature space; (2) the insensitivity of I3D features to temporal distortions; (3) the impractical sample sizes required for reliable estimation. These findings undermine FVD's reliability and show that FVD falls short as a standalone metric for video generation evaluation. After extensive analysis of a wide range of metrics and backbone architectures, we propose JEDi, the JEPA Embedding Distance, based on features derived from a Joint Embedding Predictive Architecture, measured using Maximum Mean Discrepancy with polynomial kernel. Our experiments on multiple open-source datasets show clear evidence that it is a superior alternative to the widely used FVD metric, requiring only 16% of the samples to reach its steady value, while increasing alignment with human evaluation by 34%, on average.
Efficient Design-and-Control Automation with Reinforcement Learning and Adaptive Exploration
Jiajun Fan
Hongyao Tang
Michael Przystupa
Mariano Phielipp
Santiago Miret
Seeking good designs is a central goal of many important domains, such as robotics, integrated circuits (IC), medicine, and materials scienc… (see more)e. These design problems are expensive, time-consuming, and traditionally performed by human experts. Moreover, the barriers to domain knowledge make it challenging to propose a universal solution that generalizes to different design problems. In this paper, we propose a new method called Efficient Design and Stable Control (EDiSon) for automatic design and control in different design problems. The key ideas of our method are (1) interactive sequential modeling of the design and control process and (2) adaptive exploration and design replay. To decompose the difficulty of learning design and control as a whole, we leverage sequential modeling for both the design process and control process, with a design policy to generate step-by-step design proposals and a control policy to optimize the objective by operating the design. With deep reinforcement learning (RL), the policies learn to find good designs by maximizing a reward signal that evaluates the quality of designs. Furthermore, we propose an adaptive exploration and replay mechanism based on a design memory that maintains high-quality designs generated so far. By regulating between constructing a design from scratch or replaying a design from memory to refine it, EDiSon balances the trade-off between exploration and exploitation in the design space and stabilizes the learning of the control policy. In the experiments, we evaluate our method in robotic morphology design and Tetris-based design tasks. Our framework has the potential to significantly accelerate the discovery of optimized designs across diverse domains, including automated materials discovery, by improving the exploration in design space while ensuring efficiency.
fPLSA: Learning Semantic Structures in Document Collections Using Foundation Models
Weijia Xu
Nebojsa Jojic