Learning State Reachability as a Graph in Translation Invariant Goal-based Reinforcement Learning Tasks

Hedwin BONNAVAUD, Alexandre Albore, Emmanuel Rachelson

Keywords: Graph planning, reinforcement learning, goal reaching, maze navigation

TL;DR: We solve goal-reaching navigation problems, by gradually building a reachability graph, and exploiting a reusable local, pre-trained, goal-reaching policy to navigate through this graph to reach far goals.

Abstract: Deep Reinforcement Learning proved efficient at learning universal control policies when the goal state is close enough to the starting state, or when the value function features few discontinuities. But reaching goals that require long action sequences in complex environments remains difficult. Drawing inspiration from the cognitive process which reuses learned atomic skills in a global planning procedure, we propose an algorithm which encodes reachability between abstract goals as a graph, and produces plans in this goal space. Transitions between goals rely on the exploitation of a learned policy which enjoys a property we call translation invariant local optimality, which encodes the intuition that goal-reaching skills can be reused throughout the state space. Overall, our contribution permits solving large and difficult navigation tasks, outperforming related methods from the literature.