Search Results for author: Mohammad Norouzi

Found 72 papers, 39 papers with code

NASA Neural Articulated Shape Approximation

no code implementations ECCV 2020 Boyang Deng, JP Lewis, Timothy Jeruzalski, Gerard Pons-Moll, Geoffrey Hinton, Mohammad Norouzi, Andrea Tagliasacchi

Efficient representation of articulated objects such as human bodies is an important problem in computer vision and graphics.

Palette: Image-to-Image Diffusion Models

no code implementations10 Nov 2021 Chitwan Saharia, William Chan, Huiwen Chang, Chris A. Lee, Jonathan Ho, Tim Salimans, David J. Fleet, Mohammad Norouzi

On four challenging image-to-image translation tasks (colorization, inpainting, uncropping, and JPEG decompression), Palette outperforms strong GAN and regression baselines, and establishes a new state of the art.

Colorization Denoising +4

WaveGrad 2: Iterative Refinement for Text-to-Speech Synthesis

2 code implementations17 Jun 2021 Nanxin Chen, Yu Zhang, Heiga Zen, Ron J. Weiss, Mohammad Norouzi, Najim Dehak, William Chan

The model takes an input phoneme sequence, and through an iterative refinement process, generates an audio waveform.

Speech Synthesis Text-To-Speech Synthesis

Generate, Annotate, and Learn: Generative Models Advance Self-Training and Knowledge Distillation

no code implementations11 Jun 2021 Xuanli He, Islam Nassar, Jamie Kiros, Gholamreza Haffari, Mohammad Norouzi

To obtain strong task-specific generative models, we adopt generic generative models, pretrained on open-domain data, and fine-tune them on inputs from specific tasks.

Knowledge Distillation

Learning to Efficiently Sample from Diffusion Probabilistic Models

no code implementations7 Jun 2021 Daniel Watson, Jonathan Ho, Mohammad Norouzi, William Chan

Key advantages of DDPMs include ease of training, in contrast to generative adversarial networks, and speed of generation, in contrast to autoregressive models.

Denoising Speech Synthesis

Cascaded Diffusion Models for High Fidelity Image Generation

no code implementations30 May 2021 Jonathan Ho, Chitwan Saharia, William Chan, David J. Fleet, Mohammad Norouzi, Tim Salimans

We show that cascaded diffusion models are capable of generating high fidelity images on the class-conditional ImageNet generation challenge, without any assistance from auxiliary image classifiers to boost sample quality.

Data Augmentation Image Generation +1

Autoregressive Dynamics Models for Offline Policy Evaluation and Optimization

no code implementations ICLR 2021 Michael R. Zhang, Tom Le Paine, Ofir Nachum, Cosmin Paduraru, George Tucker, Ziyu Wang, Mohammad Norouzi

This modeling choice assumes that different dimensions of the next state and reward are conditionally independent given the current state and action and may be driven by the fact that fully observable physics-based simulation environments entail deterministic transition dynamics.

Continuous Control Data Augmentation

SpeechStew: Simply Mix All Available Speech Recognition Data to Train One Large Neural Network

no code implementations5 Apr 2021 William Chan, Daniel Park, Chris Lee, Yu Zhang, Quoc Le, Mohammad Norouzi

We present SpeechStew, a speech recognition model that is trained on a combination of various publicly available speech recognition datasets: AMI, Broadcast News, Common Voice, LibriSpeech, Switchboard/Fisher, Tedlium, and Wall Street Journal.

Language Modelling Speech Recognition +1

Benchmarks for Deep Off-Policy Evaluation

3 code implementations ICLR 2021 Justin Fu, Mohammad Norouzi, Ofir Nachum, George Tucker, Ziyu Wang, Alexander Novikov, Mengjiao Yang, Michael R. Zhang, Yutian Chen, Aviral Kumar, Cosmin Paduraru, Sergey Levine, Tom Le Paine

Off-policy evaluation (OPE) holds the promise of being able to leverage large, offline datasets for both evaluating and selecting complex policies for decision making.

Continuous Control Decision Making +1

Big Self-Supervised Models Advance Medical Image Classification

no code implementations ICCV 2021 Shekoofeh Azizi, Basil Mustafa, Fiona Ryan, Zachary Beaver, Jan Freyberg, Jonathan Deaton, Aaron Loh, Alan Karthikesalingam, Simon Kornblith, Ting Chen, Vivek Natarajan, Mohammad Norouzi

Self-supervised pretraining followed by supervised fine-tuning has seen success in image recognition, especially when labeled examples are scarce, but has received limited attention in medical image analysis.

Classification Contrastive Learning +4

Demystifying Loss Functions for Classification

no code implementations1 Jan 2021 Simon Kornblith, Honglak Lee, Ting Chen, Mohammad Norouzi

It is common to use the softmax cross-entropy loss to train neural networks on classification datasets where a single class label is assigned to each example.

Classification General Classification +1

RL Unplugged: A Collection of Benchmarks for Offline Reinforcement Learning

1 code implementation NeurIPS 2020 Caglar Gulcehre, Ziyu Wang, Alexander Novikov, Thomas Paine, Sergio Gómez, Konrad Zolna, Rishabh Agarwal, Josh S. Merel, Daniel J. Mankowitz, Cosmin Paduraru, Gabriel Dulac-Arnold, Jerry Li, Mohammad Norouzi, Matthew Hoffman, Nicolas Heess, Nando de Freitas

We hope that our suite of benchmarks will increase the reproducibility of experiments and make it possible to study challenging tasks with a limited computational budget, thus making RL research both more systematic and more accessible across the community.

Offline RL

Why Do Better Loss Functions Lead to Less Transferable Features?

no code implementations NeurIPS 2021 Simon Kornblith, Ting Chen, Honglak Lee, Mohammad Norouzi

We show that many objectives lead to statistically significant improvements in ImageNet accuracy over vanilla softmax cross-entropy, but the resulting fixed feature extractors transfer substantially worse to downstream tasks, and the choice of loss has little effect when networks are fully fine-tuned on the new tasks.

Classification General Classification +1

Mastering Atari with Discrete World Models

2 code implementations ICLR 2021 Danijar Hafner, Timothy Lillicrap, Mohammad Norouzi, Jimmy Ba

The world model uses discrete representations and is trained separately from the policy.

Ranked #3 on Atari Games on Atari 2600 Skiing (using extra training data)

Atari Games

WaveGrad: Estimating Gradients for Waveform Generation

7 code implementations ICLR 2021 Nanxin Chen, Yu Zhang, Heiga Zen, Ron J. Weiss, Mohammad Norouzi, William Chan

This paper introduces WaveGrad, a conditional model for waveform generation which estimates gradients of the data density.

Speech Synthesis Text-To-Speech Synthesis

RL Unplugged: A Suite of Benchmarks for Offline Reinforcement Learning

1 code implementation24 Jun 2020 Caglar Gulcehre, Ziyu Wang, Alexander Novikov, Tom Le Paine, Sergio Gomez Colmenarejo, Konrad Zolna, Rishabh Agarwal, Josh Merel, Daniel Mankowitz, Cosmin Paduraru, Gabriel Dulac-Arnold, Jerry Li, Mohammad Norouzi, Matt Hoffman, Ofir Nachum, George Tucker, Nicolas Heess, Nando de Freitas

We hope that our suite of benchmarks will increase the reproducibility of experiments and make it possible to study challenging tasks with a limited computational budget, thus making RL research both more systematic and more accessible across the community.

Atari Games DQN Replay Dataset +1

Big Self-Supervised Models are Strong Semi-Supervised Learners

7 code implementations NeurIPS 2020 Ting Chen, Simon Kornblith, Kevin Swersky, Mohammad Norouzi, Geoffrey Hinton

The proposed semi-supervised learning algorithm can be summarized in three steps: unsupervised pretraining of a big ResNet model using SimCLRv2, supervised fine-tuning on a few labeled examples, and distillation with unlabeled examples for refining and transferring the task-specific knowledge.

Fine-tuning Self-Supervised Image Classification +1

Dynamic Programming Encoding for Subword Segmentation in Neural Machine Translation

1 code implementation ACL 2020 Xuanli He, Gholamreza Haffari, Mohammad Norouzi

This paper introduces Dynamic Programming Encoding (DPE), a new segmentation algorithm for tokenizing sentences into subword units.

Machine Translation Translation

Non-Autoregressive Machine Translation with Latent Alignments

2 code implementations EMNLP 2020 Chitwan Saharia, William Chan, Saurabh Saxena, Mohammad Norouzi

In addition, we adapt the Imputer model for non-autoregressive machine translation and demonstrate that Imputer with just 4 generation steps can match the performance of an autoregressive Transformer baseline.

Machine Translation Translation

Exemplar VAE: Linking Generative Models, Nearest Neighbor Retrieval, and Data Augmentation

1 code implementation NeurIPS 2020 Sajad Norouzi, David J. Fleet, Mohammad Norouzi

We introduce Exemplar VAEs, a family of generative models that bridge the gap between parametric and non-parametric, exemplar based generative models.

Data Augmentation Density Estimation +2

NiLBS: Neural Inverse Linear Blend Skinning

no code implementations6 Apr 2020 Timothy Jeruzalski, David I. W. Levin, Alec Jacobson, Paul Lalonde, Mohammad Norouzi, Andrea Tagliasacchi

In this technical report, we investigate efficient representations of articulated objects (e. g. human bodies), which is an important problem in computer vision and graphics.

NASA: Neural Articulated Shape Approximation

no code implementations6 Dec 2019 Boyang Deng, JP Lewis, Timothy Jeruzalski, Gerard Pons-Moll, Geoffrey Hinton, Mohammad Norouzi, Andrea Tagliasacchi

Efficient representation of articulated objects such as human bodies is an important problem in computer vision and graphics.

Don't Blame the ELBO! A Linear VAE Perspective on Posterior Collapse

no code implementations NeurIPS 2019 James Lucas, George Tucker, Roger Grosse, Mohammad Norouzi

Posterior collapse in Variational Autoencoders (VAEs) arises when the variational posterior distribution closely matches the prior for a subset of latent variables.

Variational Inference

Self-Imitation Learning via Trajectory-Conditioned Policy for Hard-Exploration Tasks

no code implementations25 Sep 2019 Yijie Guo, Jongwook Choi, Marcin Moczulski, Samy Bengio, Mohammad Norouzi, Honglak Lee

We propose a new method of learning a trajectory-conditioned policy to imitate diverse trajectories from the agent's own past experiences and show that such self-imitation helps avoid myopic behavior and increases the chance of finding a globally optimal solution for hard-exploration tasks, especially when there are misleading rewards.

Imitation Learning

Striving for Simplicity in Off-Policy Deep Reinforcement Learning

no code implementations25 Sep 2019 Rishabh Agarwal, Dale Schuurmans, Mohammad Norouzi

This paper advocates the use of offline (batch) reinforcement learning (RL) to help (1) isolate the contributions of exploitation vs. exploration in off-policy deep RL, (2) improve reproducibility of deep RL research, and (3) facilitate the design of simpler deep RL algorithms.

Atari Games Offline RL +1

Memory Based Trajectory-conditioned Policies for Learning from Sparse Rewards

no code implementations NeurIPS 2020 Yijie Guo, Jongwook Choi, Marcin Moczulski, Shengyu Feng, Samy Bengio, Mohammad Norouzi, Honglak Lee

Reinforcement learning with sparse rewards is challenging because an agent can rarely obtain non-zero rewards and hence, gradient-based optimization of parameterized policies can be incremental and slow.

Efficient Exploration Imitation Learning +1

Similarity of Neural Network Representations Revisited

7 code implementations ICML 2019 2019 Simon Kornblith, Mohammad Norouzi, Honglak Lee, Geoffrey Hinton

We introduce a similarity index that measures the relationship between representational similarity matrices and does not suffer from this limitation.

Understanding Posterior Collapse in Generative Latent Variable Models

no code implementations ICLR Workshop DeepGenStruct 2019 James Lucas, George Tucker, Roger Grosse, Mohammad Norouzi

Posterior collapse in Variational Autoencoders (VAEs) arises when the variational distribution closely matches the uninformative prior for a subset of latent variables.

Latent Variable Models Variational Inference

Learning to Generalize from Sparse and Underspecified Rewards

1 code implementation19 Feb 2019 Rishabh Agarwal, Chen Liang, Dale Schuurmans, Mohammad Norouzi

The parameters of the auxiliary reward function are optimized with respect to the validation performance of a trained policy.

Semantic Parsing

Understanding the impact of entropy on policy optimization

1 code implementation27 Nov 2018 Zafarali Ahmed, Nicolas Le Roux, Mohammad Norouzi, Dale Schuurmans

Entropy regularization is commonly used to improve policy optimization in reinforcement learning.

Contingency-Aware Exploration in Reinforcement Learning

no code implementations ICLR 2019 Jongwook Choi, Yijie Guo, Marcin Moczulski, Junhyuk Oh, Neal Wu, Mohammad Norouzi, Honglak Lee

This paper investigates whether learning contingency-awareness and controllable aspects of an environment can lead to better exploration in reinforcement learning.

Montezuma's Revenge

Sequence to Sequence Mixture Model for Diverse Machine Translation

no code implementations CONLL 2018 Xuanli He, Gholamreza Haffari, Mohammad Norouzi

In this paper, we develop a novel sequence to sequence mixture (S2SMIX) model that improves both translation diversity and quality by adopting a committee of specialized translation models rather than a single translation model.

Machine Translation Translation

Optimal Completion Distillation for Sequence Learning

2 code implementations ICLR 2019 Sara Sabour, William Chan, Mohammad Norouzi

We present Optimal Completion Distillation (OCD), a training procedure for optimizing sequence to sequence models based on edit distance.

End-To-End Speech Recognition Speech Recognition

The Importance of Generation Order in Language Modeling

no code implementations EMNLP 2018 Nicolas Ford, Daniel Duckworth, Mohammad Norouzi, George E. Dahl

Neural language models are a critical component of state-of-the-art systems for machine translation, summarization, audio transcription, and other tasks.

Language Modelling Machine Translation +1

Memory Augmented Policy Optimization for Program Synthesis and Semantic Parsing

4 code implementations NeurIPS 2018 Chen Liang, Mohammad Norouzi, Jonathan Berant, Quoc Le, Ni Lao

We present Memory Augmented Policy Optimization (MAPO), a simple and novel way to leverage a memory buffer of promising trajectories to reduce the variance of policy gradient estimate.

Combinatorial Optimization Program Synthesis +2

Discovery of Latent 3D Keypoints via End-to-end Geometric Reasoning

1 code implementation NeurIPS 2018 Supasorn Suwajanakorn, Noah Snavely, Jonathan Tompson, Mohammad Norouzi

We demonstrate this framework on 3D pose estimation by proposing a differentiable objective that seeks the optimal set of keypoints for recovering the relative pose between two views of an object.

3D Pose Estimation

Embedding Text in Hyperbolic Spaces

no code implementations WS 2018 Bhuwan Dhingra, Christopher J. Shallue, Mohammad Norouzi, Andrew M. Dai, George E. Dahl

Ideally, we could incorporate our prior knowledge of this hierarchical structure into unsupervised learning algorithms that work on text data.

Hierarchical structure Sentence Embeddings

Parallel Architecture and Hyperparameter Search via Successive Halving and Classification

1 code implementation25 May 2018 Manoj Kumar, George E. Dahl, Vijay Vasudevan, Mohammad Norouzi

We present a simple and powerful algorithm for parallel black box optimization called Successive Halving and Classification (SHAC).

Classification General Classification

Smoothed Action Value Functions for Learning Gaussian Policies

no code implementations ICML 2018 Ofir Nachum, Mohammad Norouzi, George Tucker, Dale Schuurmans

State-action value functions (i. e., Q-values) are ubiquitous in reinforcement learning (RL), giving rise to popular algorithms such as SARSA and Q-learning.

Continuous Control Q-Learning

Code Synthesis with Priority Queue Training

no code implementations ICLR 2018 Daniel A. Abolafia, Quoc V. Le, Mohammad Norouzi

We consider the task of program synthesis in the presence of a reward function over the output of programs, where the goal is to find programs with maximal rewards.

Program Synthesis

Trust-PCL: An Off-Policy Trust Region Method for Continuous Control

1 code implementation ICLR 2018 Ofir Nachum, Mohammad Norouzi, Kelvin Xu, Dale Schuurmans

When evaluated on a number of continuous control tasks, Trust-PCL improves the solution quality and sample efficiency of TRPO.

Continuous Control

Device Placement Optimization with Reinforcement Learning

1 code implementation ICML 2017 Azalia Mirhoseini, Hieu Pham, Quoc V. Le, Benoit Steiner, Rasmus Larsen, Yuefeng Zhou, Naveen Kumar, Mohammad Norouzi, Samy Bengio, Jeff Dean

Key to our method is the use of a sequence-to-sequence model to predict which subsets of operations in a TensorFlow graph should run on which of the available devices.

Language Modelling Machine Translation +1

Filtering Variational Objectives

3 code implementations NeurIPS 2017 Chris J. Maddison, Dieterich Lawson, George Tucker, Nicolas Heess, Mohammad Norouzi, andriy mnih, Arnaud Doucet, Yee Whye Teh

When used as a surrogate objective for maximum likelihood estimation in latent variable models, the evidence lower bound (ELBO) produces state-of-the-art results.

Latent Variable Models

PixColor: Pixel Recursive Colorization

no code implementations19 May 2017 Sergio Guadarrama, Ryan Dahl, David Bieber, Mohammad Norouzi, Jonathon Shlens, Kevin Murphy

Then, given the generated low-resolution color image and the original grayscale image as inputs, we train a second CNN to generate a high-resolution colorization of an image.


Neural Audio Synthesis of Musical Notes with WaveNet Autoencoders

5 code implementations ICML 2017 Jesse Engel, Cinjon Resnick, Adam Roberts, Sander Dieleman, Douglas Eck, Karen Simonyan, Mohammad Norouzi

Generative models in vision have seen rapid progress due to algorithmic improvements and the availability of high-quality image datasets.

N-gram Language Modeling using Recurrent Neural Network Estimation

no code implementations31 Mar 2017 Ciprian Chelba, Mohammad Norouzi, Samy Bengio

Experiments on a small corpus (UPenn Treebank, one million words of training data and 10k vocabulary) have found the LSTM cell with dropout to be the best model for encoding the $n$-gram state when compared with feed-forward and vanilla RNN models.

Language Modelling

Deep Value Networks Learn to Evaluate and Iteratively Refine Structured Outputs

1 code implementation ICML 2017 Michael Gygli, Mohammad Norouzi, Anelia Angelova

We approach structured output prediction by optimizing a deep value network (DVN) to precisely estimate the task loss on different output configurations for a given input.

General Classification Multi-Label Classification +1

Bridging the Gap Between Value and Policy Based Reinforcement Learning

1 code implementation NeurIPS 2017 Ofir Nachum, Mohammad Norouzi, Kelvin Xu, Dale Schuurmans

We establish a new connection between value and policy based reinforcement learning (RL) based on a relationship between softmax temporal value consistency and policy optimality under entropy regularization.


Pixel Recursive Super Resolution

no code implementations ICCV 2017 Ryan Dahl, Mohammad Norouzi, Jonathon Shlens

A low resolution image may correspond to multiple plausible high resolution images, thus modeling the super resolution process with a pixel independent conditional model often results in averaging different details--hence blurry edges.


Neural Combinatorial Optimization with Reinforcement Learning

9 code implementations29 Nov 2016 Irwan Bello, Hieu Pham, Quoc V. Le, Mohammad Norouzi, Samy Bengio

Despite the computational expense, without much engineering and heuristic designing, Neural Combinatorial Optimization achieves close to optimal results on 2D Euclidean graphs with up to 100 nodes.

Combinatorial Optimization Traveling Salesman Problem

Improving Policy Gradient by Exploring Under-appreciated Rewards

no code implementations28 Nov 2016 Ofir Nachum, Mohammad Norouzi, Dale Schuurmans

We propose a more directed exploration strategy that promotes exploration of under-appreciated reward regions.

Efficient non-greedy optimization of decision trees

no code implementations NeurIPS 2015 Mohammad Norouzi, Maxwell D. Collins, Matthew Johnson, David J. Fleet, Pushmeet Kohli

In this paper, we present an algorithm for optimizing the split functions at all levels of the tree jointly with the leaf parameters, based on a global objective.

Structured Prediction

CO2 Forest: Improved Random Forest by Continuous Optimization of Oblique Splits

no code implementations19 Jun 2015 Mohammad Norouzi, Maxwell D. Collins, David J. Fleet, Pushmeet Kohli

We develop a convex-concave upper bound on the classification loss for a one-level decision tree, and optimize the bound by stochastic gradient descent at each internal node of the tree.

General Classification Multi-class Classification

Zero-Shot Learning by Convex Combination of Semantic Embeddings

2 code implementations19 Dec 2013 Mohammad Norouzi, Tomas Mikolov, Samy Bengio, Yoram Singer, Jonathon Shlens, Andrea Frome, Greg S. Corrado, Jeffrey Dean

In other cases the semantic embedding space is established by an independent natural language processing task, and then the image transformation into that space is learned in a second stage.

Multi-label zero-shot learning

Fast Exact Search in Hamming Space with Multi-Index Hashing

2 code implementations11 Jul 2013 Mohammad Norouzi, Ali Punjani, David J. Fleet

There is growing interest in representing image data and feature descriptors using compact binary codes for fast near neighbor search.

Cartesian K-Means

1 code implementation CVPR 2013 Mohammad Norouzi, David J. Fleet

A fundamental limitation of quantization techniques like the k-means clustering algorithm is the storage and runtime cost associated with the large numbers of clusters required to keep quantization errors small and model fidelity high.

Object Recognition Quantization

Hamming Distance Metric Learning

no code implementations NeurIPS 2012 Mohammad Norouzi, David J. Fleet, Ruslan R. Salakhutdinov

Motivated by large-scale multimedia applications we propose to learn mappings from high-dimensional data to binary codes that preserve semantic similarity.

General Classification Metric Learning +2

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