Integrating Partial Order Reduction and Symmetry Elimination for Cost-Optimal Classical Planning

Pruning techniques based on partial order reduction
and symmetry elimination have recently found increasing
attention for optimal planning. Although
these techniques appear to be rather different, they
base their pruning decisions on similar ideas from
a high level perspective. In this paper, we propose
safe integrations of partial order reduction and symmetry
elimination for cost-optimal classical planning.
We show that previously proposed symmetrybased
search algorithms can safely be applied with
strong stubborn sets. In addition, we derive the notion
of symmetrical strong stubborn sets as a more
tightly integrated concept. Our experiments show
the potential of our approaches.