Clique Analysis and Bypassing in Continuous-Time Conflict-Based Search

Thayne T. Walker, Nathan R. Sturtevant, Ariel Felner

Abstract: While the study of unit-cost Multi-Agent Pathfinding (MAPF) problems has been popular, many real-world problems require continuous time and costs. In this context, this paper studies symmetry-breaking enhancements for Continuous-Time Conflict-Based Search (CCBS), a solver for continuous-time MAPF. Resolving conflict symmetries in MAPF can require an exponential amount of work. We adapt known symmetry-breaking enhancements from unit-cost domains for CCBS: bypassing and biclique constraints. We then improve upon these to produce a new state-of-the-art algorithm: CCBS with disjoint k-partite cliques (CCBS+DK). Finally, we show empirically that CCBS+DK solves for up to 20% more agents in the same amount of time when compared to previous state-of-the-art.