Planning Modulo Theories: Extending the Planning Paradigm

Considerable effort has been spent extending the scope of
planning beyond propositional domains to include, for example,
time and numbers. Each extension has been designed as a
separate specific semantic enrichment of the underlying planning
model, with its own syntax and customised integration
into a planning algorithm. Inspired by work on SAT Modulo
Theories (SMT) in the SAT community, we develop a modelling
language and planner that treat arbitrary first order theories
as parameters. We call the approach Planning Modulo
Theories (PMT). We introduce a modular language to represent
PMT problems and demonstrate its benefits over PDDL
in expressivity and compactness. We present a generalisation
of the hmax heuristic that allows our planner, PMTPlan, to
automatically reason about arbitrary theories added as modules.
Over several new and existing benchmarks, exploiting
different theories, we show that PMTPlan can significantly
out-perform an existing planner using PDDL models.