Publications

Generating physically-consistent high-resolution climate data with hard-constrained neural networks
Paula Harder
Qidong Yang
Venkatesh Ramesh
Prasanna Sattegeri
Alex Hernández-García
Campbell Watson
D. Szwarcman
David Rolnick
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.
2021-12-31
arXiv.org (preprint)
doi.org
Geometric Scattering Attention Networks
Yimeng Min
Frederik Wenkel
Guy Wolf
Geometric scattering has recently gained recognition in graph representation learning, and recent work has shown that integrating scattering… (see more) features in graph convolution networks (GCNs) can alleviate the typical oversmoothing of features in node representation learning. However, scattering often relies on handcrafted design, requiring careful selection of frequency bands via a cascade of wavelet transforms, as well as an effective weight sharing scheme to combine low- and band-pass information. Here, we introduce a new attention-based architecture to produce adaptive task-driven node representations by implicitly learning node-wise weights for combining multiple scattering and GCN channels in the network. We show the resulting geometric scattering attention network (GSAN) outperforms previous networks in semi-supervised node classification, while also enabling a spectral study of extracted information by examining node-wise attention weights.
2021-12-31
IEEE International Conference on Acoustics, Speech and Signal Processing (unknown)
doi.org
arxiv.org
GitHub repositories with links to academic papers: Public access, traceability, and evolution
Supatsara Wattanakriengkrai
Bodin Chinthanet
Hideaki Hata
Raula Gaikovina Kula
Christoph Treude
Jin L.C. Guo
Kenichi Matsumoto
2021-12-31
Journal of Systems and Software (published)
doi.org
arxiv.org
Goal-driven optimization of single-neuron properties in artificial networks reveals regularization role of neural diversity and adaptation in the brain
Victor Geadah
Stefan Horoi
Giancarlo Kerg
Guy Wolf
Guillaume Lajoie
Neurons in the brain have rich and adaptive input-output properties. Features such as diverse f-I curves and spike frequency adaptation are … (see more)known to place single neurons in optimal coding regimes when facing changing stimuli. Yet, it is still unclear how brain circuits exploit single neuron flexibility, and how network-level requirements may have shaped such cellular function. To answer this question, a multi-scaled approach is needed where the computations of single neurons and of neural circuits must be considered as a complete system. In this work, we use artificial neural networks to systematically investigate single neuron input-output adaptive mechanisms, optimized in an end-to-end fashion. Throughout the optimization process, each neuron has the liberty to modify its nonlinear activation function, parametrized to mimic f-I curves of biological neurons, and to learn adaptation strategies to modify activation functions in real-time during a task. We find that such networks show much-improved robustness to noise and changes in input statistics. Importantly, we find that this procedure recovers precise coding strategies found in biological neurons, such as gain scaling and fractional order differentiation/integration. Using tools from dynamical systems theory, we analyze the role of these emergent single neuron properties and argue that neural diversity and adaptation plays an active regularization role that enables neural circuits to optimally propagate information across time.
2021-12-31
(published)
www.semanticscholar.org
GrowSpace: Learning How to Shape Plants
Yasmeen Hitti
Ionelia Buzatu
Manuel Del Verme
Mark Lefsrud
Florian Golemo
Audrey Durand
Plants are dynamic systems that are integral to our existence and survival. Plants face environment changes and adapt over time to their sur… (see more)rounding conditions. We argue that plant responses to an environmental stimulus are a good example of a real-world problem that can be approached within a reinforcement learning (RL)framework. With the objective of controlling a plant by moving the light source, we propose GrowSpace, as a new RL benchmark. The back-end of the simulator is implemented using the Space Colonisation Algorithm, a plant growing model based on competition for space. Compared to video game RL environments, this simulator addresses a real-world problem and serves as a test bed to visualize plant growth and movement in a faster way than physical experiments. GrowSpace is composed of a suite of challenges that tackle several problems such as control, multi-stage learning,fairness and multi-objective learning. We provide agent baselines alongside case studies to demonstrate the difficulty of the proposed benchmark.
2021-12-31
AIAFS @ AAAI Conference on Artificial Intelligence (published)
doi.org
openreview.net
Harvesting Mature Relation Extraction Models from Limited Seed Knowledge: A Self-Development Framework for DS Rule Expansion
Raphael Hoffmann
Congle Zhang
Xiao Ling
Yankai Lin
Shiqi Shen
Zhiyuan Liu
Huanbo Luan
Christopher D Manning
M. Surdeanu
John Bauer
Adriana Romero
Pietro Lio’
Yoshua Bengio
Xuanhui Wang
Cheng Li
Nadav Golbandi
Bendersky Marc
Najork. 2018
The
Wentao Wu … (see 2 more)
Hongsong Li
Haixun Wang
Distantly-supervised relation extraction 001 (DSRE) is an effective method to scale relation 002 extraction (RE) to large unlabeled corpora … (see more)003 with the utilization of knowledge bases (KBs), 004 but suffers from the scale of KBs and the 005 introduced noise. 006 To alleviate the above two problems, we 007 propose a novel framework called S elf-008 devel O pment r U le ex P ansion ( SOUP ), which 009 starts from limited amount of labeled data 010 and continuously produces low-noise labels on 011 large-scaled unlabeled data by a growing learn-012 able logical rules set. 013 Specifically, SOUP achieves a mutual enhance-014 ment of RE model and logical rules set, first 015 a RE model is trained on the labeled data to 016 summarize the knowledge, then the knowledge 017 is utilized to explore candidate rules from unla-018 beled data, finally high-quality candidates are 019 selected in a graph-based ranking manner to ex-020 tend the logical rules set and new rule-labeled 021 data are provided for better RE model training. 022 Experiments on wiki20 dataset demonstrate 023 that, with limited seed knowledge from small-024 scaled manually labeled data, SOUP achieves 025 significant improvement compared to baselines 026 by producing continuous growth of both logical 027 rules and the RE model, and that labeling noise 028 of SOUP is much less than DS. Furthermore, 029 RE model enhanced by SOUP with 1.6k logical 030 rules learned from prior knowledge could pro-031 duce an equivalent performance to the model 032 trained on data labeled in DS manner by 72k 033 relational facts of KBs. 034
2021-12-31
(published)
www.semanticscholar.org
Heterogeneous Supervised Topic Models
Dhanya Sridhar
Hal Daumé III
David Blei
Researchers in the social sciences are often interested in the relationship between text and an outcome of interest, where the goal is to bo… (see more)th uncover latent patterns in the text and predict outcomes for unseen texts. To this end, this paper develops the heterogeneous supervised topic model (HSTM), a probabilistic approach to text analysis and prediction. HSTMs posit a joint model of text and outcomes to find heterogeneous patterns that help with both text analysis and prediction. The main benefit of HSTMs is that they capture heterogeneity in the relationship between text and the outcome across latent topics. To fit HSTMs, we develop a variational inference algorithm based on the auto-encoding variational Bayes framework. We study the performance of HSTMs on eight datasets and find that they consistently outperform related methods, including fine-tuned black-box models. Finally, we apply HSTMs to analyze news articles labeled with pro- or anti-tone. We find evidence of differing language used to signal a pro- and anti-tone.
2021-12-31
Transactions of the Association for Computational Linguistics (published)
doi.org
How Transferable Are Features in Convolutional Neural Network Acoustic Models across Languages?
Jessica A.F. Thompson
Marc Schönwiesner
Yoshua Bengio
Daniel Willett
Characterization of the representations learned in intermediate layers of deep networks can provide valuable insight into the nature of a ta… (see more)sk and can guide the development of well-tailored learning strategies. Here we study convolutional neural network (CNN)-based acoustic models in the context of automatic speech recognition. Adapting a method proposed by [1], we measure the transferability of each layer between English, Dutch and German to assess their language-specificity. We observed three distinct regions of transferability: (1) the first two layers were entirely transferable between languages, (2) layers 2–8 were also highly transferable but we found some evidence of language specificity, (3) the subsequent fully connected layers were more language specific but could be successfully finetuned to the target language. To further probe the effect of weight freezing, we performed follow-up experiments using freeze-training [2]. Our results are consistent with the observation that CNNs converge ‘bottom up’ during training and demonstrate the benefit of freeze training, especially for transfer learning.
2021-12-31
IEEE International Conference on Acoustics, Speech and Signal Processing (unknown)
doi.org
IIRC: Incremental Implicitly-Refined Classification
Mohamed Abdelsalam
Mojtaba Faramarzi
Shagun Sodhani
Sarath Chandar
We introduce the "Incremental Implicitly-Refined Classi-fication (IIRC)" setup, an extension to the class incremental learning setup where t… (see more)he incoming batches of classes have two granularity levels. i.e., each sample could have a high-level (coarse) label like "bear" and a low-level (fine) label like "polar bear". Only one label is provided at a time, and the model has to figure out the other label if it has already learnfed it. This setup is more aligned with real-life scenarios, where a learner usually interacts with the same family of entities multiple times, discovers more granularity about them, while still trying not to forget previous knowledge. Moreover, this setup enables evaluating models for some important lifelong learning challenges that cannot be easily addressed under the existing setups. These challenges can be motivated by the example "if a model was trained on the class bear in one task and on polar bear in another task, will it forget the concept of bear, will it rightfully infer that a polar bear is still a bear? and will it wrongfully associate the label of polar bear to other breeds of bear?". We develop a standardized benchmark that enables evaluating models on the IIRC setup. We evaluate several state-of-the-art lifelong learning algorithms and highlight their strengths and limitations. For example, distillation-based methods perform relatively well but are prone to incorrectly predicting too many labels per image. We hope that the proposed setup, along with the benchmark, would provide a meaningful problem setting to the practitioners
2021-12-31
IEEE/CVF Conference on Computer Vision and Pattern Recognition (unknown)
doi.org
arxiv.org
Image Retrieval from Contextual Descriptions
Benno Krojer
Vaibhav Adlakha
Vibhav Vineet
Yash Goyal
Edoardo Ponti
Siva Reddy
The ability to integrate context, including perceptual and temporal cues, plays a pivotal role in grounding the meaning of a linguistic utte… (see more)rance. In order to measure to what extent current vision-and-language models master this ability, we devise a new multimodal challenge, Image Retrieval from Contextual Descriptions (ImageCoDe). In particular, models are tasked with retrieving the correct image from a set of 10 minimally contrastive candidates based on a contextual description.As such, each description contains only the details that help distinguish between images.Because of this, descriptions tend to be complex in terms of syntax and discourse and require drawing pragmatic inferences. Images are sourced from both static pictures and video frames.We benchmark several state-of-the-art models, including both cross-encoders such as ViLBERT and bi-encoders such as CLIP, on ImageCoDe.Our results reveal that these models dramatically lag behind human performance: the best variant achieves an accuracy of 20.9 on video frames and 59.4 on static pictures, compared with 90.8 in humans.Furthermore, we experiment with new model variants that are better equipped to incorporate visual and temporal context into their representations, which achieve modest gains. Our hope is that ImageCoDE will foster progress in grounded language understanding by encouraging models to focus on fine-grained visual differences.
2021-12-31
Association for Computational Linguistics (published)
doi.org
arxiv.org
Improved DC-Free Run-Length Limited 4B6B Codes for Concatenated Schemes
Elie Ngomseu Mambou
Thibaud Tonnellier
Warren J. Gross
In this letter, we introduce a class of improved DC-free 4B6B codes in terms of error correction capabilities for a serially concatenated ar… (see more)chitecture. There are billions of different codebooks that can be derived from the 16 codewords contained in the traditional 4B6B code as per the IEEE 802.15.7 standard for visible light communication (VLC). These codebooks can be classified based on distances properties which determine their error correction performances. The traditional 4B6B code is suitable for hard-decision decoding, however, when a soft decoder is used like in a serially concatenated architecture, that code becomes obsolete. Simulations show that the proposed 4B6B code concatenated with forward error correction (FEC) codes, has better performance compared to state-of-the-art schemes such as the original 4B6B code, the enhanced Miller code, the Manchester code, the 5B10B code and the (0,4) 2/3 RLL code.
2021-12-31
IEEE Access (published)
doi.org
Improved Detection of Chronic Obstructive Pulmonary Disease at Chest CT Using the Mean Curvature of Isophotes
Peter Savadjiev
Benoit Gallix
Morteza Rezanejad
Sahir Bhatnagar
Alexandre Semionov
Kaleem Siddiqi
Reza Forghani
Caroline Reinhold
David H. Eidelman
Ronald J. Dandurand
Purpose To determine if the mean curvature of isophotes (MCI), a standard computer vision technique, can be used to improve detection of chr… (see more)onic obstructive pulmonary disease (COPD) at chest CT. Materials and Methods In this retrospective study, chest CT scans were obtained in 243 patients with COPD and 31 controls (among all 274: 151 women [mean age, 70 years; range, 44-90 years] and 123 men [mean age, 71 years; range, 29-90 years]) from two community practices between 2006 and 2019. A convolutional neural network (CNN) architecture was trained on either CT images or CT images transformed through the MCI algorithm. Separately, a linear classification based on a single feature derived from the MCI computation (called hMCI1) was also evaluated. All three models were evaluated with cross-validation, using precision-macro and recall-macro metrics, that is, the mean of per-class precision and recall values, respectively (the latter being equivalent to balanced accuracy). Results Linear classification based on hMCI1 resulted in a higher recall-macro relative to the CNN trained and applied on CT images (0.85 [95% CI: 0.84, 0.86] vs 0.77 [95% CI: 0.75, 0.79]) but with a similar reduction in precision-macro (0.66 [95% CI: 0.65, 0.67] vs 0.77 [95% CI: 0.75, 0.79]). The CNN model trained and applied on MCI-transformed images had a higher recall-macro (0.85 [95% CI: 0.83, 0.87] vs 0.77 [95% CI: 0.75, 0.79]) and precision-macro (0.85 [95% CI: 0.83, 0.87] vs 0.77 [95% CI: 0.75, 0.79]) relative to the CNN trained and applied on CT images. Conclusion The MCI algorithm may be valuable toward the automated detection and diagnosis of COPD on chest CT scans as part of a CNN-based pipeline or with stand-alone features.Keywords: Chronic Obstructive Pulmonary Disease, Quantification, Lung, CT Supplemental material is available for this article. See also the invited commentary by Vannier in this issue.© RSNA, 2021.
2021-12-31
Radiology: Artificial Intelligence (published)
doi.org