Exploiting Path Refinement Abstraction in Domain Transition Graphs.

Partial Refinement A-Star (PRA�) is an abstraction technique,
based on clustering nearby nodes in graphs, useful
in large path-planning problems. Abstracting the underlying
graph yields a simpler problem whose solution can be
used, by refinement, as a guide to a solution to the original
problem. A fruitful way to view domain independent planning
problems is as a collection of multi-valued variables that
must perform synchronised transitions through graphs of possible
values, where the edges are defined by the domain actions.
Planning involves finding efficient paths through Domain
Transition Graphs (DTGs). In problems where these
graphs are large, planning can be prohibitively expensive. In
this paper we explore two ways to exploit PRA� in DTGs.