Publications

Learning Task Decomposition with Ordered Memory Policy Network
Yuchen Lu
Yikang Shen
Siyuan Zhou
Aaron Courville
Joshua B. Tenenbaum
Chuang Gan
Many complex real-world tasks are composed of several levels of sub-tasks. Humans leverage these hierarchical structures to accelerate the l… (voir plus)earning process and achieve better generalization. In this work, we study the inductive bias and propose Ordered Memory Policy Network (OMPN) to discover subtask hierarchy by learning from demonstration. The discovered subtask hierarchy could be used to perform task decomposition, recovering the subtask boundaries in an unstruc-tured demonstration. Experiments on Craft and Dial demonstrate that our modelcan achieve higher task decomposition performance under both unsupervised and weakly supervised settings, comparing with strong baselines. OMPN can also bedirectly applied to partially observable environments and still achieve higher task decomposition performance. Our visualization further confirms that the subtask hierarchy can emerge in our model.
2021-01-01
ICLR (publié)
openreview.net
openreview.net
Learning a Universal Template for Few-shot Dataset Generalization
Eleni Triantafillou
Hugo Larochelle
Richard Zemel
Vincent Dumoulin
2021-01-01
ICML (publié)
proceedings.mlr.press
arxiv.org
Learning with Gradient Descent and Weakly Convex Losses
Dominic Richards
Michael Rabbat
We study the learning performance of gradient descent when the empirical risk is weakly convex, namely, the smallest negative eigenvalue of … (voir plus)the empirical risk's Hessian is bounded in magnitude. By showing that this eigenvalue can control the stability of gradient descent, generalisation error bounds are proven that hold under a wider range of step sizes compared to previous work. Out of sample guarantees are then achieved by decomposing the test error into generalisation, optimisation and approximation errors, each of which can be bounded and traded off with respect to algorithmic parameters, sample size and magnitude of this eigenvalue. In the case of a two layer neural network, we demonstrate that the empirical risk can satisfy a notion of local weak convexity, specifically, the Hessian's smallest eigenvalue during training can be controlled by the normalisation of the layers, i.e., network scaling. This allows test error guarantees to then be achieved when the population risk minimiser satisfies a complexity assumption. By trading off the network complexity and scaling, insights are gained into the implicit bias of neural network scaling, which are further supported by experimental findings.
2021-01-01
AISTATS (publié)
proceedings.mlr.press
arxiv.org
Machine Learning for Combinatorial Optimization: a Methodological Tour d'Horizon
Yoshua Bengio
Andrea Lodi
Antoine Prouvost
2021-01-01
Eur. J. Oper. Res. (publié)
doi.org
arxiv.org
MICo: Improved representations via sampling-based state similarity for Markov decision processes
Pablo Samuel Castro
Tyler Kastner
Prakash Panangaden
Mark Rowland
We present a new behavioural distance over the state space of a Markov decision process, and demonstrate the use of this distance as an effe… (voir plus)ctive means of shaping the learnt representations of deep reinforcement learning agents. While existing notions of state similarity are typically difficult to learn at scale due to high computational cost and lack of sample-based algorithms, our newly-proposed distance addresses both of these issues. In addition to providing detailed theoretical analyses, we provide empirical evidence that learning this distance alongside the value function yields structured and informative representations, including strong results on the Arcade Learning Environment benchmark.
openreview.net
MICo: Learning improved representations via sampling-based state similarity for Markov decision processes
Pablo Samuel Castro
Tyler Kastner
Prakash Panangaden
Mark Rowland
We present a new behavioural distance over the state space of a Markov decision process, and demonstrate the use of this distance as an eff… (voir plus)ective means of shaping the learnt representations of deep reinforcement learning agents. While existing notions of state similarity are typically difficult to learn at scale due to high computational cost and lack of sample-based algorithms, our newly-proposed distance addresses both of these issues. In addition to providing detailed theoretical analysis
2021-01-01
arXiv.org (prépublication)
dblp.uni-trier.de
Multi-Agent Estimation and Filtering for Minimizing Team Mean-Squared Error
Mohammad Afshari
Aditya Mahajan
Motivated by estimation problems arising in autonomous vehicles and decentralized control of unmanned aerial vehicles, we consider multi-age… (voir plus)nt estimation and filtering problems in which multiple agents generate state estimates based on decentralized information and the objective is to minimize a coupled mean-squared error which we call team mean-square error. We call the resulting estimates as minimum team mean-squared error (MTMSE) estimates. We show that MTMSE estimates are different from minimum mean-squared error (MMSE) estimates. We derive closed-form expressions for MTMSE estimates, which are linear function of the observations where the corresponding gain depends on the weight matrix that couples the estimation error. We then consider a filtering problem where a linear stochastic process is monitored by multiple agents which can share their observations (with delay) over a communication graph. We derive expressions to recursively compute the MTMSE estimates. To illustrate the effectiveness of the proposed scheme we consider an example of estimating the distances between vehicles in a platoon and show that MTMSE estimates significantly outperform MMSE estimates and consensus Kalman filtering estimates.
2021-01-01
IEEE Transactions on Signal Processing (publié)
doi.org
arxiv.org
Multi-Domain Balanced Sampling Improves Out-of-Generalization of Chest X-ray Pathology Prediction Models
Enoch Amoatey Tetteh
Joseph D Viviano
Yoshua Bengio
David Scott Krueger
Joseph Paul Cohen
Learning models that generalize under different distribution shifts in medical imaging has been a long-standing research challenge. There ha… (voir plus)ve been several proposals for efficient and robust visual representation learning among vision research practitioners, especially in the sensitive and critical biomedical domain. In this paper, we propose an idea for out-of-distribution generalization of chest X-ray pathologies that uses a simple balanced batch sampling technique. We observed that balanced sampling between the multiple training datasets improves the performance over baseline models trained without balancing. Code for this work is available on Github. 1
Multilevel Approaches for the Critical Node Problem
Andrea Baggio
Margarida Carvalho
Andrea Lodi
Andrea Tramontani
2021-01-01
Operational Research (publié)
doi.org
Multimodal Audio-textual Architecture for Robust Spoken Language Understanding
Dmitriy Serdyuk
Yongqiang Wang
Christian Fue-730
Anuj Kumar
Baiyang Liu
Yoshua Bengio
Edwin Simonnet
Sahar Ghannay
Nathalie Camelin
Tandem spoken language understanding 001 (SLU) systems suffer from the so-called 002 automatic speech recognition (ASR) error 003 propagatio… (voir plus)n problem. Additionally, as the 004 ASR is not optimized to extract semantics, but 005 solely the linguistic content, relevant semantic 006 cues might be left out of its transcripts. In 007 this work, we propose a multimodal language 008 understanding (MLU) architecture to mitigate 009 these problems. Our solution is based on 010 two compact unidirectional long short-term 011 memory (LSTM) models that encode speech 012 and text information. A fusion layer is also 013 used to fuse audio and text embeddings. 014 Two fusion strategies are explored: a simple 015 concatenation of these embeddings and a 016 cross-modal attention mechanism that learns 017 the contribution of each modality. The first 018 approach showed to be the optimal solution 019 to robustly extract semantic information from 020 audio-textual data. We found that attention 021 is less effective at testing time when the text 022 modality is corrupted. Our model is evaluated 023 on three SLU datasets and robustness is tested 024 using ASR outputs from three off-the-shelf 025 ASR engines. Results show that the proposed 026 approach effectively mitigates the ASR error 027 propagation problem for all datasets. 028
Neural Approximate Sufficient Statistics for Implicit Models
Yanzhi Chen
Dinghuai Zhang
Michael U. Gutmann
Aaron Courville
Zhanxing Zhu
We consider the fundamental problem of how to automatically construct summary statistics for implicit generative models where the evaluation… (voir plus) of likelihood function is intractable but sampling / simulating data from the model is possible. The idea is to frame the task of constructing sufficient statistics as learning mutual information maximizing representation of the data. This representation is computed by a deep neural network trained by a joint statistic-posterior learning strategy. We apply our approach to both traditional approximate Bayesian computation (ABC) and recent neural likelihood approaches, boosting their performance on a range of tasks.
2021-01-01
ICLR (publié)
openreview.net
openreview.net
A Novel and Dedicated Machine Learning Model for Malware Classification
Miles Q. Li
Benjamin Fung
Philippe Charland
Steven H. H. Ding
: Malicious executables are comprised of functions that can be represented in assembly code. In the assembly code mining literature, many so… (voir plus)ftware reverse engineering tools have been created to disassemble executables, search function clones, and find vulnerabilities, among others. The development of a machine learning-based malware classification model that can simultaneously achieve excellent classification performance and provide insightful interpretation for the classification results remains to be a hot research topic. In this paper, we propose a novel and dedicated machine learning model for the research problem of malware classification. Our proposed model generates assembly code function clusters based on function representation learning and provides excellent interpretability for the classification results. It does not require a large or balanced dataset to train which meets the situation of real-life scenarios. Experiments show that our proposed approach outperforms previous state-of-the-art malware classification models and provides meaningful interpretation of classification results.
2021-01-01
International Conference on Software and Data Technologies (publié)
doi.org