  While the study of unit-cost Multi-Agent Pathfinding (MAPF) problems has been
popular, many real-world problems require continuous time and costs due to
various movement models. 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 enhancements from unit-cost domains
for CCBS: bypassing, which resolves cost symmetries and biclique constraints
which resolve spatial conflict symmetries. We formulate a novel combination of
biclique constraints with disjoint splitting for spatial conflict symmetries.
Finally, we show empirically that these enhancements yield a statistically
significant performance improvement versus previous state of the art, solving
problems for up to 10% or 20% more agents in the same amount of time on dense
graphs.
