🤖 AI Summary
This work addresses the problem of policy synthesis in Markov decision processes (MDPs) under entropy-based constraints that enforce concentration of state visitation distributions. It formalizes entropy maximization as a policy synthesis objective for the first time, establishes its computational complexity, and introduces a novel method combining convex duality theory with invariant synthesis to handle nonlinear entropy constraints in a conditionally complete manner. By systematically analyzing the roles of memory and randomization in policies, the approach effectively synthesizes and verifies entropy-constrained policies across multiple benchmark instances, substantially extending the expressiveness and applicability of existing policy synthesis frameworks.
📝 Abstract
We consider the problem of synthesizing control policies that enforce a concentration property on the state distributions of a stochastic system. We present a formalization of this problem in terms of synthesizing strategies for maintaining an entropy-based objective in Markov Decision Processes (MDPs). We first show that even relaxed versions of this problem are complexity-theoretically hard. We then present a sound and (conditionally) relatively complete method to verify and synthesize strategies for such entropy objectives. The main challenge is the non-linear nature of such objectives, and our approach addresses this by exploiting and combining ideas from convex duality and invariant synthesis. We also investigate the role of memory and randomization in ensuring entropy objectives. Finally, we implement our ideas to evaluate our approach empirically on a few illustrative benchmarks.