Hindsight Credit Assignment
Anna Harutyunyan, Will Dabney, Thomas Mésnard, Mohammad Gheshlaghi Azar, Bilal Piot, Nicolas Heess, Hado P. van Hasselt, Greg Wayne, Satinder Pal Singh, Doina Precup, Rémi Munos · arXiv (Cornell University) · 2019
We consider the problem of efficient credit assignment in reinforcement learning. In order to efficiently and meaningfully utilize new data, we propose to explicitly assign credit to past decisions based on the likelihood of them having led to the observed outcome. This approach uses new information in hindsight, rather than employing foresight. Somewhat surprisingly, we show that value functions can be rewritten through this lens, yielding a new family of algorithms. We study the properties of these algorithms, and empirically show that they successfully address important credit assignment challenges, through a set of illustrative tasks.