Learning discrete state abstractions with deep variational inference
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Abstraction is crucial for effective sequential decision making in domains with large state spaces. In this work, we propose a variational information bottleneck method for learning approximate bisimulations, a type of state abstraction. We use a deep neural net encoder to map states onto continuous embeddings. The continuous latent space is then compressed into a discrete representation using an action-conditioned hidden Markov model, which is trained end-to-end with the neural network. Our method is suited for environments with high-dimensional states and learns from a stream of experience collected by an agent acting in a Markov decision process. Through a learned discrete abstract model, we can efficiently plan for unseen goals in a multi-goal Reinforcement Learning setting. We test our method in simplified robotic manipulation domains with image states. We also compare it against previous model-based approaches to finding bisimulations in discrete grid-world-like environments.
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