Publications

CADet: Fully Self-Supervised Anomaly Detection With Contrastive Learning
Charles Guille-escuret
Pau Rodríguez
David Vázquez
Ioannis Mitliagkas
Joao Monteiro
Handling out-of-distribution (OOD) samples has become a major stake in the real-world deployment of machine learning systems. This work expl… (voir plus)ores the use of self-supervised contrastive learning to the simultaneous detection of two types of OOD samples: unseen classes and adversarial perturbations. First, we pair self-supervised contrastive learning with the maximum mean discrepancy (MMD) two-sample test. This approach enables us to robustly test whether two independent sets of samples originate from the same distribution, and we demonstrate its effectiveness by discriminating between CIFAR-10 and CIFAR-10.1 with higher confidence than previous work. Motivated by this success, we introduce CADet (Contrastive Anomaly Detection), a novel method for OOD detection of single samples. CADet draws inspiration from MMD, but leverages the similarity between contrastive transformations of a same sample. CADet outperforms existing adversarial detection methods in identifying adversarially perturbed samples on ImageNet and achieves comparable performance to unseen label detection methods on two challenging benchmarks: ImageNet-O and iNaturalist. Significantly, CADet is fully self-supervised and requires neither labels for in-distribution samples nor access to OOD examples.
2023-12-11
Conference on Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net
ClimateSet: A Large-Scale Climate Model Dataset for Machine Learning
Julia Kaltenborn
Charlotte Emilie Elektra Lange
Venkatesh Ramesh
Philippe Brouillard
Yaniv Gurwicz
Chandni Nagda
Jakob Runge
Peer Nowack
David Rolnick
Climate models have been key for assessing the impact of climate change and simulating future climate scenarios. The machine learning (ML) c… (voir plus)ommunity has taken an increased interest in supporting climate scientists' efforts on various tasks such as climate model emulation, downscaling, and prediction tasks. Many of those tasks have been addressed on datasets created with single climate models. However, both the climate science and ML communities have suggested that to address those tasks at scale, we need large, consistent, and ML-ready climate model datasets. Here, we introduce ClimateSet, a dataset containing the inputs and outputs of 36 climate models from the Input4MIPs and CMIP6 archives. In addition, we provide a modular dataset pipeline for retrieving and preprocessing additional climate models and scenarios. We showcase the potential of our dataset by using it as a benchmark for ML-based climate model emulation. We gain new insights about the performance and generalization capabilities of the different ML models by analyzing their performance across different climate models. Furthermore, the dataset can be used to train an ML emulator on several climate models instead of just one. Such a "super emulator" can quickly project new climate change scenarios, complementing existing scenarios already provided to policymakers. We believe ClimateSet will create the basis needed for the ML community to tackle climate-related tasks at scale.
2023-12-11
Neural Information Processing Systems (Accept (Poster))
doi.org
openreview.net
Contrastive Retrospection: honing in on critical steps for rapid learning and generalization in RL
Chen Sun
Wannan Yang
Thomas Jiralerspong
Dane Malenfant
Benjamin Alsbury-Nealy
Yoshua Bengio
Blake Richards
In real life, success is often contingent upon multiple critical steps that are distant in time from each other and from the final reward. T… (voir plus)hese critical steps are challenging to identify with traditional reinforcement learning (RL) methods that rely on the Bellman equation for credit assignment. Here, we present a new RL algorithm that uses offline contrastive learning to hone in on these critical steps. This algorithm, which we call Contrastive Retrospection (ConSpec), can be added to any existing RL algorithm. ConSpec learns a set of prototypes for the critical steps in a task by a novel contrastive loss and delivers an intrinsic reward when the current state matches one of the prototypes. The prototypes in ConSpec provide two key benefits for credit assignment: (i) They enable rapid identification of all the critical steps. (ii) They do so in a readily interpretable manner, enabling out-of-distribution generalization when sensory features are altered. Distinct from other contemporary RL approaches to credit assignment, ConSpec takes advantage of the fact that it is easier to retrospectively identify the small set of steps that success is contingent upon (and ignoring other states) than it is to prospectively predict reward at every taken step. ConSpec greatly improves learning in a diverse set of RL tasks. The code is available at the link: https://github.com/sunchipsster1/ConSpec
2023-12-11
Advances in Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net
DiffPack: A Torsional Diffusion Model for Autoregressive Protein Side-Chain Packing
Yangtian Zhang
Zuobai Zhang
Bozitao Zhong
Sanchit Misra
Jian Tang
Proteins play a critical role in carrying out biological functions, and their 3D structures are essential in determining their functions. Ac… (voir plus)curately predicting the conformation of protein side-chains given their backbones is important for applications in protein structure prediction, design and protein-protein interactions. Traditional methods are computationally intensive and have limited accuracy, while existing machine learning methods treat the problem as a regression task and overlook the restrictions imposed by the constant covalent bond lengths and angles. In this work, we present DiffPack, a torsional diffusion model that learns the joint distribution of side-chain torsional angles, the only degrees of freedom in side-chain packing, by diffusing and denoising on the torsional space. To avoid issues arising from simultaneous perturbation of all four torsional angles, we propose autoregressively generating the four torsional angles from
2023-12-11
Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net
Double Gumbel Q-Learning
David Yu-tung Hui
Aaron Courville
Pierre-Luc Bacon
2023-12-11
Neural Information Processing Systems (Accept (spotlight))
doi.org
openreview.net
DynGFN: Towards Bayesian Inference of Gene Regulatory Networks with GFlowNets
Lazar Atanackovic
Alexander Tong
Bo Wang
Leo J. Lee
Yoshua Bengio
Jason Hartford
One of the grand challenges of cell biology is inferring the gene regulatory network (GRN) which describes interactions between genes and th… (voir plus)eir products that control gene expression and cellular function. We can treat this as a causal discovery problem but with two non-standard challenges: (1) regulatory networks are inherently cyclic so we should not model a GRN as a directed acyclic graph (DAG), and (2) observations have significant measurement noise, so for typical sample sizes there will always be a large equivalence class of graphs that are likely given the data, and we want methods that capture this uncertainty. Existing methods either focus on challenge (1), identifying cyclic structure from dynamics, or on challenge (2) learning complex Bayesian posteriors over DAGs, but not both. In this paper we leverage the fact that it is possible to estimate the "velocity" of gene expression with RNA velocity techniques to develop an approach that addresses both challenges. Because we have access to velocity information, we can treat the Bayesian structure learning problem as a problem of sparse identification of a dynamical system, capturing cyclic feedback loops through time. Since our objective is to model uncertainty over discrete structures, we leverage Generative Flow Networks (GFlowNets) to estimate the posterior distribution over the combinatorial space of possible sparse dependencies. Our results indicate that our method learns posteriors that better encapsulate the distributions of cyclic structures compared to counterpart state-of-the-art Bayesian structure learning approaches.
2023-12-11
Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net
An Empirical Investigation of the Role of Pre-training in Lifelong Learning
Sanket Vaibhav Mehta
Darshan Patil
Sarath Chandar
Emma Strubell
The lifelong learning paradigm in machine learning is an attractive alternative to the more prominent isolated learning scheme not only due … (voir plus)to its resemblance to biological learning but also its potential to reduce energy waste by obviating excessive model re-training. A key challenge to this paradigm is the phenomenon of catastrophic forgetting. With the increasing popularity and success of pre-trained models in machine learning, we pose the question: What role does pre-training play in lifelong learning, specifically with respect to catastrophic forgetting? We investigate existing methods in the context of large, pre-trained models and evaluate their performance on a variety of text and image classification tasks, including a large-scale study using a novel data set of 15 diverse NLP tasks. Across all settings, we observe that generic pre-training implicitly alleviates the effects of catastrophic forgetting when learning multiple tasks sequentially compared to randomly initialized models. We then further investigate why pre-training alleviates forgetting in this setting. We study this phenomenon by analyzing the loss landscape, finding that pre-trained weights appear to ease forgetting by leading to wider minima. Based on this insight, we propose jointly optimizing for current task loss and loss basin sharpness to explicitly encourage wider basins during sequential fine-tuning. We show that this optimization approach outperforms several state-of-the-art task-sequential continual learning algorithms across multiple settings, occasionally even without retaining a memory that scales in size with the number of tasks.
2023-12-11
Conference on Neural Information Processing Systems (Accept (Poster))
doi.org
openreview.net
Equivariant Adaptation of Large Pretrained Models
Arnab Kumar Mondal
Siba Smarak Panigrahi
Sékou-Oumar Kaba
Sai Rajeswar
Siamak Ravanbakhsh
Equivariant networks are specifically designed to ensure consistent behavior with respect to a set of input transformations, leading to high… (voir plus)er sample efficiency and more accurate and robust predictions. However, redesigning each component of prevalent deep neural network architectures to achieve chosen equivariance is a difficult problem and can result in a computationally expensive network during both training and inference. A recently proposed alternative towards equivariance that removes the architectural constraints is to use a simple canonicalization network that transforms the input to a canonical form before feeding it to an unconstrained prediction network. We show here that this approach can effectively be used to make a large pretrained network equivariant. However, we observe that the produced canonical orientations can be misaligned with those of the training distribution, hindering performance. Using dataset-dependent priors to inform the canonicalization function, we are able to make large pretrained models equivariant while maintaining their performance. This significantly improves the robustness of these models to deterministic transformations of the data, such as rotations. We believe this equivariant adaptation of large pretrained models can help their domain-specific applications with known symmetry priors.
2023-12-11
Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net
Feature Likelihood Divergence: Evaluating the Generalization of Generative Models Using Samples
Marco Jiralerspong
Avishek (Joey) Bose
Ian Gemp
Chongli Qin
Yoram Bachrach
Gauthier Gidel
The past few years have seen impressive progress in the development of deep generative models capable of producing high-dimensional, complex… (voir plus), and photo-realistic data. However, current methods for evaluating such models remain incomplete: standard likelihood-based metrics do not always apply and rarely correlate with perceptual fidelity, while sample-based metrics, such as FID, are insensitive to overfitting, i.e., inability to generalize beyond the training set. To address these limitations, we propose a new metric called the Feature Likelihood Divergence (FLD), a parametric sample-based metric that uses density estimation to provide a comprehensive trichotomic evaluation accounting for novelty (i.e., different from the training samples), fidelity, and diversity of generated samples. We empirically demonstrate the ability of FLD to identify overfitting problem cases, even when previously proposed metrics fail. We also extensively evaluate FLD on various image datasets and model classes, demonstrating its ability to match intuitions of previous metrics like FID while offering a more comprehensive evaluation of generative models. Code is available at https://github.com/marcojira/fld.
2023-12-11
Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net
For SALE: State-Action Representation Learning for Deep Reinforcement Learning
Scott Fujimoto
Wei-Di Chang
Edward J. Smith
Shixiang Shane Gu
Doina Precup
David Meger
In the field of reinforcement learning (RL), representation learning is a proven tool for complex image-based tasks, but is often overlooked… (voir plus) for environments with low-level states, such as physical control problems. This paper introduces SALE, a novel approach for learning embeddings that model the nuanced interaction between state and action, enabling effective representation learning from low-level states. We extensively study the design space of these embeddings and highlight important design considerations. We integrate SALE and an adaptation of checkpoints for RL into TD3 to form the TD7 algorithm, which significantly outperforms existing continuous control algorithms. On OpenAI gym benchmark tasks, TD7 has an average performance gain of 276.7% and 50.7% over TD3 at 300k and 5M time steps, respectively, and works in both the online and offline settings.
2023-12-11
Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net
Formalizing locality for normative synaptic plasticity models
Colin Bredenberg
Ezekiel Williams
Cristina Savin
Blake Richards
Guillaume Lajoie
2023-12-11
Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net
GAUCHE: A Library for Gaussian Processes in Chemistry
Ryan-Rhys Griffiths
Leo Klarner
Henry Moss
Aditya Ravuri
Sang Truong
Bojana Rankovic
Samuel Stanton
Yuanqi Du
Arian Jamasb
Gary Tom
Julius Schwartz
Austin Tripp
Aryan Deshwal
Gregory Kell
Anthony Bourached
Alex J. Chan
Jacob Moss
Chengzhi Guo
Simon Frieder
Alpha A. Lee … (voir 8 de plus)
Philippe Schwaller
Jian Tang
Johannes Durholt
Saudamini Chaurasia
Ji Won Park
Felix Strieth-Kalthoff
Bingqing Cheng
Alán Aspuru-Guzik
We introduce GAUCHE, a library for GAUssian processes in CHEmistry. Gaussian processes have long been a cornerstone of probabilistic machine… (voir plus) learning, affording particular advantages for uncertainty quantification and Bayesian optimisation. Extending Gaussian processes to chemical representations, however, is nontrivial, necessitating kernels defined over structured inputs such as graphs, strings and bit vectors. By defining such kernels in GAUCHE, we seek to open the door to powerful tools for uncertainty quantification and Bayesian optimisation in chemistry. Motivated by scenarios frequently encountered in experimental chemistry, we showcase applications for GAUCHE in molecular discovery and chemical reaction optimisation. The codebase is made available at https://github.com/leojklarner/gauche
2023-12-11
Conference on Neural Information Processing Systems (Accept (poster))
doi.org
openreview.net