Minimizing Makespan with Conflict-Based Search for Optimal Multi-Agent Path Finding

Amir Maliah, Dor Atzmon, Ariel Felner

Keywords: Makespan, Conflict-Based Search, Multi-Agent Path Finding

Abstract:

Conflict-based search (CBS) is a prominent algorithm that optimally
solves the Multi-Agent Path Finding problem (MAPF). There are two
common objective functions for MAPF: Makespan (MKS), the time
elapsed until the task ends, and Sum-Of-Costs (SOC), the sum of
costs of all paths. Most existing MAPF algorithms, including CBS,
were not designed particularly for minimizing MKS. In this paper,
we show that CBS can be redefined as a framework that can be finetuned
to different objectives. We introduce an instantiation of this
framework for minimizing MKS. Its low-level solves a new search
setting which we call Extended Bounded-Cost Search. Our experiments
show that our new algorithm can significantly outperform
previous algorithms for MKS. Moreover, we discuss two extensions
of MKS which are also members of our general framework.

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Submission Number: 23