Publications

Efficient Continual Learning Ensembles in Neural Network Subspaces
Thang Doan
Seyed Iman Mirzadeh
Mehrdad Farajtabar
A growing body of research in continual learning focuses on the catastrophic forgetting problem. While many attempts have been made to allev… (voir plus)iate this problem, the majority of the methods assume a single model in the continual learning setup. In this work, we question this assumption and show that employing ensemble models can be a simple yet effective method to improve continual performance. However, the training and inference cost of ensembles can increase linearly with the number of models. Motivated by this limitation, we leverage the recent advances in the deep learning optimization literature, such as mode connectivity and neural network subspaces, to derive a new method that is both computationally advantageous and can outperform the state-of-the-art continual learning algorithms
Embedding Signals on Graphs with Unbalanced Diffusion Earth Mover's Distance
In modern relational machine learning it is common to encounter large graphs that arise via interactions or similarities between observation… (voir plus)s in many domains. Further, in many cases the target entities for analysis are actually signals on such graphs. We propose to compare and organize such datasets of graph signals by using an earth mover's distance (EMD) with a geodesic cost over the underlying graph. Typically, EMD is computed by optimizing over the cost of transporting one probability distribution to another over an underlying metric space. However, this is inefficient when computing the EMD between many signals. Here, we propose an unbalanced graph EMD that efficiently embeds the unbalanced EMD on an underlying graph into an
Enhanced Biomedical Knowledge Discovery From Unstructured Text Using Contextual Embeddings
Iz Beltagy
Kyle Lo
Arman Cohan. 2019
Scib-500
R´ejean Ducharme
P Vincent
Rishi Bommasani
Kelly Davis
Claire Cardie
Billy Chiu
Sampo Pyysalo
Ivan Vuli´c
Extracting knowledge from large, unstruc-001 tured text corpora presents a challenge. Re-002 cently, authors have utilized unsupervised, 003… (voir plus) static word embeddings to uncover "latent 004 knowledge" contained within domain-specific 005 scientific corpora. Here semantic-similarity 006 measures between representations of concepts, 007 objects or entities were used to predict re-008 lationships, which were later verified using 009 physical methods. Static language models 010 have recently been surpassed at most down-011 stream tasks by massively pre-trained, contex-012 tual language models like BERT. Some have 013 postulated that contextualized embeddings po-014 tentially yield word representations superior 015 to static ones for knowledge-discovery pur-016 poses. In an effort to address this ques-017 tion, two biomedically-trained BERT models 018 (BioBERT, SciBERT) were used to encode 019 n = 500, 1000 or 5000 sentences containing 020 words of interest extracted from a biomedical 021 corpus (Coronavirus Open Research Dataset). 022 The n representations for the words of inter-023 est were subsequently extracted and then ag-024 gregated to yield static-equivalent word rep-025 resentations. These words belonged to the 026 vocabularies of intrinsic benchmarking tools 027 for the biomedical domain (Bio-SimVerb and 028 Bio-SimLex), which assess quality of word 029 representations using semantic-similarity and 030 relatedness measures. Using intrinsic bench-031 marking tasks, feasibility of using contextual-032 ized word representations for knowledge dis-033 covery tasks can be assessed: Word represen-034 tations that better encode described reality are 035 expected to perform better (i.e. closer to do-036 main experts). As postulated, BERT embed-037 dings outperform static counterparts
Equivariant Networks for Crystal Structures
Sékou-Oumar Kaba
Supervised learning with deep models has tremendous potential for applications in materials science. Recently, graph neural networks have be… (voir plus)en used in this context, drawing direct inspiration from models for molecules. However, materials are typically much more structured than molecules, which is a feature that these models do not leverage. In this work, we introduce a class of models that are equivariant with respect to crystalline symmetry groups. We do this by defining a generalization of the message passing operations that can be used with more general permutation groups, or that can alternatively be seen as defining an expressive convolution operation on the crystal graph. Empirically, these models achieve competitive results with state-of-the-art on property prediction tasks.
Extended Abstract Track
Jason Hartford
Christian Shewmake
Simone Azeglio
Arianna Di Bernardo
Nina Miolane
Extracting Person Names from User Generated Text: Named-Entity Recognition for Combating Human Trafficking
f-Cal: Aleatoric uncertainty quantification for robot perception via calibrated neural regression
While modern deep neural networks are performant perception modules, performance (accuracy) alone is insufficient, particularly for safety-c… (voir plus)ritical robotic applications such as self-driving vehicles. Robot autonomy stacks also require these otherwise blackbox models to produce reliable and calibrated measures of confidence on their predictions. Existing approaches estimate uncertainty from these neural network perception stacks by modifying network architectures, inference procedure, or loss functions. However, in general, these methods lack calibration, meaning that the predictive uncertainties do not faithfully represent the true underlying uncertainties (process noise). Our key insight is that calibration is only achieved by imposing constraints across multiple examples, such as those in a mini-batch; as opposed to existing approaches which only impose constraints per-sample, often leading to overconfident (thus miscalibrated) uncertainty estimates. By enforcing the distribution of outputs of a neural network to resemble a target distribution by minimizing an
Feeding What You Need by Understanding What You Learned
Fangli Xu
Bo Long
Siliang Tang
Lingfei Wu
Few-Shot Pidgin Text Adaptation via Contrastive Fine-Tuning
Ernie Chang
Jesujoba Oluwadara Alabi
Vera Demberg
The surging demand for multilingual dialogue systems often requires a costly labeling process for each language addition. For low resource l… (voir plus)anguages, human annotators are continuously tasked with the adaptation of resource-rich language utterances for each new domain. However, this prohibitive and impractical process can often be a bottleneck for low resource languages that are still without proper translation systems nor parallel corpus. In particular, it is difficult to obtain task-specific low resource language annotations for the English-derived creoles (e.g. Nigerian and Cameroonian Pidgin). To address this issue, we utilize the pretrained language models i.e. BART which has shown great potential in language generation/understanding – we propose to finetune the BART model to generate utterances in Pidgin by leveraging the proximity of the source and target languages, and utilizing positive and negative examples in constrastive training objectives. We collected and released the first parallel Pidgin-English conversation corpus in two dialogue domains and showed that this simple and effective technique is suffice to yield impressive results for English-to-Pidgin generation, which are two closely-related languages.
Findings of the WMT’22 Shared Task on Large-Scale Machine Translation Evaluation for African Languages
Md Mahfuz Ibn Alam
Antonios Anastasopoulos
Akshita Bhagia
Marta R. Costa-jussa
Jesse Dodge
Fahim Faisal
Christian Federmann
Natalia N. Fedorova
Francisco S. Guzm'an
Sergey Koshelev
Jean Maillard
Vukosi Marivate
Jonathan Mbuya
Alexandre Mourachko
Safiyyah Saleem
Guillaume Wenzek
We present the results of the WMT’22 SharedTask on Large-Scale Machine Translation Evaluation for African Languages. The shared taskinclud… (voir plus)ed both a data and a systems track, alongwith additional innovations, such as a focus onAfrican languages and extensive human evaluation of submitted systems. We received 14system submissions from 8 teams, as well as6 data track contributions. We report a largeprogress in the quality of translation for Africanlanguages since the last iteration of this sharedtask: there is an increase of about 7.5 BLEUpoints across 72 language pairs, and the average BLEU scores went from 15.09 to 22.60.
Flexible Diffusion Modeling of Long Videos
William Harvey
Saeid Naderiparizi
Vaden Masrani
Christian Dietrich Weilbach
Frank N. Wood
We present a framework for video modeling based on denoising diffusion probabilistic models that produces long-duration video completions in… (voir plus) a variety of realistic environments. We introduce a generative model that can at test-time sample any arbitrary subset of video frames conditioned on any other subset and present an architecture adapted for this purpose. Doing so allows us to efficiently compare and optimize a variety of schedules for the order in which frames in a long video are sampled and use selective sparse and long-range conditioning on previously sampled frames. We demonstrate improved video modeling over prior work on a number of datasets and sample temporally coherent videos over 25 minutes in length. We additionally release a new video modeling dataset and semantically meaningful metrics based on videos generated in the CARLA autonomous driving simulator.
Forgetting Enhances Episodic Control With Structured Memories
Blake A. Richards
Forgetting is a normal process in healthy brains, and evidence suggests that the mammalian brain forgets more than is required based on limi… (voir plus)tations of mnemonic capacity. Episodic memories, in particular, are liable to be forgotten over time. Researchers have hypothesized that it may be beneficial for decision making to forget episodic memories over time. Reinforcement learning offers a normative framework in which to test such hypotheses. Here, we show that a reinforcement learning agent that uses an episodic memory cache to find rewards in maze environments can forget a large percentage of older memories without any performance impairments, if they utilize mnemonic representations that contain structural information about space. Moreover, we show that some forgetting can actually provide a benefit in performance compared to agents with unbounded memories. Our analyses of the agents show that forgetting reduces the influence of outdated information and states which are not frequently visited on the policies produced by the episodic control system. These results support the hypothesis that some degree of forgetting can be beneficial for decision making, which can help to explain why the brain forgets more than is required by capacity limitations.