Portrait of David Rolnick

David Rolnick

Core Academic Member
Canada CIFAR AI Chair
Assistant Professor, McGill University, School of Computer Science
Adjunct Professor, Université de Montréal, Department of Computer Science and Operations Research
Research Topics
AI and Sustainability
AI for Science
Applied Machine Learning
Biodiversity
Building Energy Management Systems
Climate
Climate Change
Climate Change AI
Climate Modeling
Climate Science
Climate Variable Downscaling
Computer Vision
Conservation Technology
Energy Systems
Forest Monitoring
Machine Learning and Climate Change
Machine Learning for Physical Sciences
Machine Learning in Climate Modeling
Machine Learning Theory
Out-of-Distribution (OOD) Detection
Remote Sensing
Satellite Remote Sensing
Time Series Forecasting
Vegetation

Biography

David Rolnick is an assistant professor at McGill University’s School of Computer Science, a core academic member of Mila – Quebec Artificial Intelligence Institute and holds a Canada CIFAR AI Chair. Rolnick’s work focuses on applications of machine learning to help address climate change. He is the co-founder and chair of Climate Change AI, and scientific co-director of Sustainability in the Digital Age. After completing his PhD in applied mathematics at the Massachusetts Institute of Technology (MIT), he was a NSF Mathematical Sciences Postdoctoral Research Fellow, an NSF Graduate Research Fellow and a Fulbright Scholar. He was named to MIT Technology Review’s “35 Innovators Under 35” in 2021.

Current Students

Collaborating Alumni - McGill University
Collaborating researcher - Cambridge University
Co-supervisor :
Collaborating researcher
Postdoctorate - McGill University
Collaborating researcher - McGill University
Postdoctorate - McGill University
Independent visiting researcher - Politecnico di Milano
Collaborating researcher - Johannes Kepler University
Master's Research - McGill University
Independent visiting researcher - Université de Montréal
Collaborating researcher - Polytechnique Montréal Montréal
Principal supervisor :
Collaborating researcher - University of Waterloo
Co-supervisor :
Independent visiting researcher - University of Washington
Master's Research - McGill University
Master's Research - McGill University
Collaborating researcher - University of Tübingen
Independent visiting researcher - Karlsruhe Institute of Technology
Independent visiting researcher
Collaborating researcher - Karlsruhe Institute of Technology
Collaborating Alumni - Université de Montréal
Principal supervisor :
Collaborating researcher
Collaborating researcher - Ecole Polytechnique Montréal Fédérale de Lausanne (EPFL)
Co-supervisor :
Collaborating researcher - 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… (see more)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 … (see more)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… (see more)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… (see more) 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… (see more)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… (see more)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… (see more) 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… (see more)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 … (see more)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.