  Although reinforcement learning (RL) can solve many challenging sequential
decision making problems, achieving zero-shot transfer across related tasks
remains a challenge. The difficulty lies in finding a good representation for
the current task so that the agent understands how it relates to previously
seen tasks. To achieve zero-shot transfer, we introduce the function encoder, a
representation learning algorithm which represents a function as a weighted
combination of learned, non-linear basis functions. By using a function encoder
to represent the reward function or the transition function, the agent has
information on how the current task relates to previously seen tasks via a
coherent vector representation. Thus, the agent is able to achieve transfer
between related tasks at run time with no additional training. We demonstrate
state-of-the-art data efficiency, asymptotic performance, and training
stability in three RL fields by augmenting basic RL algorithms with a function
encoder task representation.
