Portrait de David Rolnick

David Rolnick

Membre académique principal
Chaire en IA Canada-CIFAR
Professeur adjoint, McGill University, École d'informatique
Professeur associé, Université de Montréal, Département d'informatique et de recherche opérationnelle
Sujets de recherche
Apprentissage automatique appliqué
Apprentissage automatique dans la modélisation climatique
Apprentissage automatique et changement climatique
Apprentissage automatique pour les sciences physiques
Biodiversité
Changement climatique
Climat
Détection hors distribution (OOD)
IA et durabilité
IA pour la science
IA pour le changement climatique
Modélisation climatique
Prévision des séries temporelles
Réduction d'échelle des variables climatiques
Science du climat
Surveillance des forêts
Systèmes de gestion de l'énergie des bâtiments
Systèmes énergétiques
Technologie de conservation
Télédétection
Télédétection par satellite
Théorie de l'apprentissage automatique
Végétation
Vision par ordinateur

Biographie

David Rolnick est professeur adjoint et titulaire d’une chaire en IA Canada-CIFAR à l'École d'informatique de l'Université McGill et membre académique principal de Mila – Institut québécois d’intelligence artificielle. Ses travaux portent sur les applications de l'apprentissage automatique dans la lutte contre le changement climatique. Il est cofondateur et président de Climate Change AI et codirecteur scientifique de Sustainability in the Digital Age. David Rolnick a obtenu un doctorat en mathématiques appliquées du Massachusetts Institute of Technology (MIT). Il a été chercheur postdoctoral en sciences mathématiques à la National Science Foundation (NSF), chercheur diplômé à la NSF et boursier Fulbright. Il a figuré sur la liste des « 35 innovateurs de moins de 35 ans » de la MIT Technology Review en 2021.

Étudiants actuels

Collaborateur·rice de recherche - Cambridge University
Co-superviseur⋅e :
Collaborateur·rice de recherche
Collaborateur·rice de recherche - McGill
Postdoctorat - McGill
Collaborateur·rice de recherche
Collaborateur·rice de recherche
Visiteur de recherche indépendant - Politecnico di Milano
Collaborateur·rice de recherche - Johannes Kepler University
Maîtrise recherche - McGill
Visiteur de recherche indépendant - Université de Montréal
Collaborateur·rice de recherche - Polytechnique Montréal
Superviseur⋅e principal⋅e :
Collaborateur·rice de recherche - University of Waterloo
Co-superviseur⋅e :
Visiteur de recherche indépendant - University of Washington
Maîtrise recherche - McGill
Maîtrise recherche - McGill
Collaborateur·rice de recherche - University of Tübingen
Visiteur de recherche indépendant - Karlsruhe Institute of Technology
Visiteur de recherche indépendant
Collaborateur·rice de recherche - Karlsruhe Institute of Technology
Collaborateur·rice alumni - UdeM
Superviseur⋅e principal⋅e :
Collaborateur·rice de recherche
Collaborateur·rice de recherche - Ecole Polytechnique Fédérale de Lausanne (EPFL)
Co-superviseur⋅e :
Collaborateur·rice de recherche - Technical University of Munich

Publications

Deep ReLU Networks Preserve Expected Length
Assessing the complexity of functions computed by a neural network helps us understand how the network will learn and generalize. One natura… (voir plus)l measure of complexity is how the network distorts length - if the network takes a unit-length curve as input, what is the length of the resulting curve of outputs? It has been widely believed that this length grows exponentially in network depth. We prove that in fact this is not the case: the expected length distortion does not grow with depth, and indeed shrinks slightly, for ReLU networks with standard random initialization. We also generalize this result by proving upper bounds both for higher moments of the length distortion and for the distortion of higher-dimensional volumes. These theoretical results are corroborated by our experiments.
Generating physically-consistent high-resolution climate data with hard-constrained neural networks
Prasanna Sattegeri
Campbell Watson
D. Szwarcman
The availability of reliable, high-resolution climate and weather data is important to inform long-term decisions on climate adaptation and … (voir plus)mitigation and to guide rapid responses to extreme events. Forecasting models are limited by computational costs and therefore often can only make coarse resolution predictions. Statistical downscaling can provide an efficient method of upsampling low-resolution data. In this field, deep learning has been applied successfully, often us-ing image super-resolution methods from computer vision. Despite achieving visually compelling results in some cases, such models often violate conservation laws when predicting physical variables. In order to conserve important physical quantities, we develop methods that guarantee physical constraints are satisfied by a deep downscaling model while also increasing their performance according to traditional metrics. We introduce two ways of constraining the network: A renor-malization layer added to the end of the neural network and a successive approach that scales with increasing upsampling factors. We show the applicability of our methods across different popular architectures and upsampling factors using ERA5 reanalysis data.
TIML: Task-Informed Meta-Learning for crop type mapping
Labeled datasets for agriculture are extremely spatially imbalanced. When developing algorithms for data-sparse regions, a previously explor… (voir plus)ed approach is to use transfer learning from data-rich regions. While standard transfer learning approaches typically leverage only direct inputs and outputs, geospatial imagery and agricultural data is rich in metadata that can inform transfer learning algorithms, such as the spatial coordinates of data-points. We build on previous work exploring use of meta-learning to crop type mapping in data-sparse regions and introduce task-informed meta-learning (TIML), an augmentation to model-agnostic meta-learning which takes advantage of this metadata. We apply TIML to the CropHarvest dataset, a global dataset of agricultural class labels paired with remote sensing data. In addition, we introduce the concept of forgetfulness when training meta-learning models on many similar tasks to mitigate memorization of training tasks. We find that TIML significantly improves average performance across the CropHarvest evaluation tasks compared to a range of benchmark models, measured using AUC ROC and F1 scores.
Techniques for Symbol Grounding with SATNet
Sever Topan
Many experts argue that the future of artificial intelligence is limited by the field's ability to integrate symbolic logical reasoning into… (voir plus) deep learning architectures. The recently proposed differentiable MAXSAT solver, SATNet, was a breakthrough in its capacity to integrate with a traditional neural network and solve visual reasoning problems. For instance, it can learn the rules of Sudoku purely from image examples. Despite its success, SATNet was shown to succumb to a key challenge in neurosymbolic systems known as the Symbol Grounding Problem: the inability to map visual inputs to symbolic variables without explicit supervision ("label leakage"). In this work, we present a self-supervised pre-training pipeline that enables SATNet to overcome this limitation, thus broadening the class of problems that SATNet architectures can solve to include datasets where no intermediary labels are available at all. We demonstrate that our method allows SATNet to attain full accuracy even with a harder problem setup that prevents any label leakage. We additionally introduce a proofreading method that further improves the performance of SATNet architectures, beating the state-of-the-art on Visual Sudoku.
Hidden Hypergraphs, Error-Correcting Codes, and Critical Learning in Hopfield Networks
Christopher Hillar
Tenzin Chan
Rachel Taubman
In 1943, McCulloch and Pitts introduced a discrete recurrent neural network as a model for computation in brains. The work inspired breakthr… (voir plus)oughs such as the first computer design and the theory of finite automata. We focus on learning in Hopfield networks, a special case with symmetric weights and fixed-point attractor dynamics. Specifically, we explore minimum energy flow (MEF) as a scalable convex objective for determining network parameters. We catalog various properties of MEF, such as biological plausibility, and then compare to classical approaches in the theory of learning. Trained Hopfield networks can perform unsupervised clustering and define novel error-correcting coding schemes. They also efficiently find hidden structures (cliques) in graph theory. We extend this known connection from graphs to hypergraphs and discover n-node networks with robust storage of 2Ω(n1−ϵ) memories for any ϵ>0. In the case of graphs, we also determine a critical ratio of training samples at which networks generalize completely.
ClimART: A Benchmark Dataset for Emulating Atmospheric Radiative Transfer in Weather and Climate Models
Jason N. S. Cole
Howard Barker
Numerical simulations of Earth's weather and climate require substantial amounts of computation. This has led to a growing interest in repla… (voir plus)cing subroutines that explicitly compute physical processes with approximate machine learning (ML) methods that are fast at inference time. Within weather and climate models, atmospheric radiative transfer (RT) calculations are especially expensive. This has made them a popular target for neural network-based emulators. However, prior work is hard to compare due to the lack of a comprehensive dataset and standardized best practices for ML benchmarking. To fill this gap, we build a large dataset, ClimART, with more than 10 million samples from present, pre-industrial, and future climate conditions, based on the Canadian Earth System Model. ClimART poses several methodological challenges for the ML community, such as multiple out-of-distribution test sets, underlying domain physics, and a trade-off between accuracy and inference speed. We also present several novel baselines that indicate shortcomings of datasets and network architectures used in prior work.
Digitizing a sustainable future
Lucia A. Reisch
Lucas Joppa
Peter Howson
Artur Gil
Panayiota Alevizou
Nina Michaelidou
Ruby Appiah-Campbell
Tilman Santarius
Susanne Köhler
Massimo Pizzol
Pia-Johanna Schweizer
Dipti Srinivasan
Lynn H. Kaack
Priya L. Donti
DC3: A learning method for optimization with hard constraints
Priya L. Donti
J Zico Kolter
Large optimization problems with hard constraints arise in many settings, yet classical solvers are often prohibitively slow, motivating the… (voir plus) use of deep networks as cheap"approximate solvers."Unfortunately, naive deep learning approaches typically cannot enforce the hard constraints of such problems, leading to infeasible solutions. In this work, we present Deep Constraint Completion and Correction (DC3), an algorithm to address this challenge. Specifically, this method enforces feasibility via a differentiable procedure, which implicitly completes partial solutions to satisfy equality constraints and unrolls gradient-based corrections to satisfy inequality constraints. We demonstrate the effectiveness of DC3 in both synthetic optimization tasks and the real-world setting of AC optimal power flow, where hard constraints encode the physics of the electrical grid. In both cases, DC3 achieves near-optimal objective values while preserving feasibility.
Geo-Spatiotemporal Features and Shape-Based Prior Knowledge for Fine-grained Imbalanced Data Classification
Charles A. Kantor
Léonard Boussioux
Emmanuel Jehanno
Alexandra Luccioni
Hugues Talbot
Fine-grained classification aims at distinguishing between items with similar global perception and patterns, but that differ by minute deta… (voir plus)ils. Our primary challenges come from both small inter-class variations and large intra-class variations. In this article, we propose to combine several innovations to improve fine-grained classification within the use-case of wildlife, which is of practical interest for experts. We utilize geo-spatiotemporal data to enrich the picture information and further improve the performance. We also investigate state-of-the-art methods for handling the imbalanced data issue.
Reverse-engineering deep ReLU networks
Konrad Paul Kording
It has been widely assumed that a neural network cannot be recovered from its outputs, as the network depends on its parameters in a highly … (voir plus)nonlinear way. Here, we prove that in fact it is often possible to identify the architecture, weights, and biases of an unknown deep ReLU network by observing only its output. Every ReLU network defines a piecewise linear function, where the boundaries between linear regions correspond to inputs for which some neuron in the network switches between inactive and active ReLU states. By dissecting the set of region boundaries into components associated with particular neurons, we show both theoretically and empirically that it is possible to recover the weights of neurons and their arrangement within the network, up to isomorphism.