Adaptive Belief Discretization for POMDP Planning
  Partially Observable Markov Decision Processes (POMDP) is a widely used model
to represent the interaction of an environment and an agent, under state
uncertainty. Since the agent does not observe the environment state, its
uncertainty is typically represented through a probabilistic belief. While the
set of possible beliefs is infinite, making exact planning intractable, the
belief space's complexity (and hence planning complexity) is characterized by
its covering number. Many POMDP solvers uniformly discretize the belief space
and give the planning error in terms of the (typically unknown) covering
number. We instead propose an adaptive belief discretization scheme, and give
its associated planning error. We furthermore characterize the covering number
with respect to the POMDP parameters. This allows us to specify the exact
memory requirements on the planner, needed to bound the value function error.
We then propose a novel, computationally efficient solver using this scheme. We
demonstrate that our algorithm is highly competitive with the state of the art
in a variety of scenarios.
