Pierre-Luc Bacon

2024-01-01

AISTATS (published)

doi.org

Block-State Transformers

Jonathan Pilault

Mahan Fathi

Orhan Firat

2023-09-21

NeurIPS.cc/2023/Conference (poster)

Double Gumbel Q-Learning.

David Yu-Tung Hui

Aaron Courville

Policy Optimization in a Noisy Neighborhood: On Return Landscapes in Continuous Control

Nathan Rahn

Pierluca D'Oro

Harley Wiltzer

Marc Gendron-Bellemare

Deep reinforcement learning agents for continuous control are known to exhibit significant instability in their performance over time. In th… (see more)is work, we provide a fresh perspective on these behaviors by studying the return landscape: the mapping between a policy and a return. We find that popular algorithms traverse noisy neighborhoods of this landscape, in which a single update to the policy parameters leads to a wide range of returns. By taking a distributional view of these returns, we map the landscape, characterizing failure-prone regions of policy space and revealing a hidden dimension of policy quality. We show that the landscape exhibits surprising structure by finding simple paths in parameter space which improve the stability of a policy. To conclude, we develop a distribution-aware procedure which finds such paths, navigating away from noisy neighborhoods in order to improve the robustness of a policy. Taken together, our results provide new insight into the optimization, evaluation, and design of agents.

When Do Transformers Shine in RL? Decoupling Memory from Credit Assignment

Tianwei Ni

Michel Ma

Benjamin Eysenbach

Reinforcement learning (RL) algorithms face two distinct challenges: learning effective representations of past and present observations, an… (see more)d determining how actions influence future returns. Both challenges involve modeling long-term dependencies. The Transformer architecture has been very successful to solve problems that involve long-term dependencies, including in the RL domain. However, the underlying reason for the strong performance of Transformer-based RL methods remains unclear: is it because they learn effective memory, or because they perform effective credit assignment? After introducing formal definitions of memory length and credit assignment length, we design simple configurable tasks to measure these distinct quantities. Our empirical results reveal that Transformers can enhance the memory capability of RL algorithms, scaling up to tasks that require memorizing observations

Goal-conditioned GFlowNets for Controllable Multi-Objective Molecular Design

Julien Roy

Emmanuel Bengio

In recent years, in-silico molecular design has received much attention from the machine learning community. When designing a new compound f… (see more)or pharmaceutical applications, there are usually multiple properties of such molecules that need to be optimised: binding energy to the target, synthesizability, toxicity, EC50, and so on. While previous approaches have employed a scalarization scheme to turn the multi-objective problem into a preference-conditioned single objective, it has been established that this kind of reduction may produce solutions that tend to slide towards the extreme points of the objective space when presented with a problem that exhibits a concave Pareto front. In this work we experiment with an alternative formulation of goal-conditioned molecular generation to obtain a more controllable conditional model that can uniformly explore solutions along the entire Pareto front.

2023-06-23

ICML.cc/2023/Workshop/DeployableGenerativeAI (published)

doi.org

Block-State Transformers

Mahan Fathi

Jonathan Pilault

Orhan Firat

2023-06-15

ArXiv (preprint)

Block-State Transformers

Mahan Fathi

Jonathan Pilault

Orhan Firat

State space models (SSMs) have shown impressive results on tasks that require modeling long-range dependencies and efficiently scale to long… (see more) sequences owing to their subquadratic runtime complexity. Originally designed for continuous signals, SSMs have shown superior performance on a plethora of tasks, in vision and audio; however, SSMs still lag Transformer performance in Language Modeling tasks. In this work, we propose a hybrid layer named Block-State Transformer (BST), that internally combines an SSM sublayer for long-range contextualization, and a Block Transformer sublayer for short-term representation of sequences. We study three different, and completely parallelizable, variants that integrate SSMs and block-wise attention. We show that our model outperforms similar Transformer-based architectures on language modeling perplexity and generalizes to longer sequences. In addition, the Block-State Transformer demonstrates more than tenfold increase in speed at the layer level compared to the Block-Recurrent Transformer when model parallelization is employed.

2023-06-15

ArXiv (preprint)

Block-State Transformers

Mahan Fathi

Jonathan Pilault

Orhan Firat

2023-06-15

ArXiv (preprint)

Block-State Transformers

Mahan Fathi

Jonathan Pilault

Orhan Firat

2023-06-15

ArXiv (preprint)

Block-State Transformers

Mahan Fathi

Jonathan Pilault

Orhan Firat

2023-06-15

ArXiv (preprint)

Sample-Efficient Reinforcement Learning by Breaking the Replay Ratio Barrier

Pierluca D'Oro

Max Schwarzer

Evgenii Nikishin

Marc Gendron-Bellemare

Aaron Courville

Increasing the replay ratio, the number of updates of an agent's parameters per environment interaction, is an appealing strategy for improv… (see more)ing the sample efficiency of deep reinforcement learning algorithms. In this work, we show that fully or partially resetting the parameters of deep reinforcement learning agents causes better replay ratio scaling capabilities to emerge. We push the limits of the sample efficiency of carefully-modified algorithms by training them using an order of magnitude more updates than usual, significantly improving their performance in the Atari 100k and DeepMind Control Suite benchmarks. We then provide an analysis of the design choices required for favorable replay ratio scaling to be possible and discuss inherent limits and tradeoffs.

2023-02-01

ICLR.cc/2023/Conference (notable)