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Daniel Lawson

PhD - Université de Montréal
Supervisor
Co-supervisor
Research Topics
Deep Learning
Reinforcement Learning
Robotics

Publications

Imagining Goals for Policy Generalization with Geometric Horizon Models
Training from offline data has allowed for substantial progress in domains such as robotics, leading to general-purpose policies that can be… (see more) easily applied zero-shot or efficiently finetuned for downstream tasks. However, training policies on offline data can lead to poor generalization, both due to the choice of modeling objective and from learning from a static dataset. In this work, we focus on the challenging task of zero-shot goal generalization, where a policy is evaluated on unseen tasks that require reusing its existing knowledge (compositional generalization). An avenue for improving a policy's generalization is through generating new experience through world models; however, such generation has proven difficult for longer horizons. Thus, to alleviate this issue, we propose TD-Aug, sampling from a geometric horizon model, which allows for directly imagining novel outcomes that can be achieved through composing existing knowledge. We demonstrate that training on these future outcomes as goals for goal-conditioned BC and offline RL policies improves generalization in stitching-based OGBench tasks.
Self-Predictive Representations for Combinatorial Generalization in Behavioral Cloning
Behavioral cloning (BC) methods trained with supervised learning (SL) are an effective way to learn policies from human demonstrations in do… (see more)mains like robotics. Goal-conditioning these policies enables a single generalist policy to capture diverse behaviors contained within an offline dataset. While goal-conditioned behavior cloning (GCBC) methods can perform well on in-distribution training tasks, they do not necessarily generalize zero-shot to tasks that require conditioning on novel state-goal pairs, i.e. combinatorial generalization. In part, this limitation can be attributed to a lack of temporal consistency in the state representation learned by BC; if temporally related states are encoded to similar latent representations, then the out-of-distribution gap for novel state-goal pairs would be reduced. Hence, encouraging this temporal consistency in the representation space should facilitate combinatorial generalization. Successor representations, which encode the distribution of future states visited from the current state, nicely encapsulate this property. However, previous methods for learning successor representations have relied on contrastive samples, temporal-difference (TD) learning, or both. In this work, we propose a simple yet effective representation learning objective,