  We formalize and study the multi-goal task assignment and path finding
(MG-TAPF) problem from theoretical and algorithmic perspectives. The MG-TAPF
problem is to compute an assignment of tasks to agents, where each task
consists of a sequence of goal locations, and collision-free paths for the
agents that visit all goal locations of their assigned tasks in sequence.
Theoretically, we prove that the MG-TAPF problem is NP-hard to solve optimally.
We present algorithms that build upon algorithmic techniques for the
multi-agent path finding problem and solve the MG-TAPF problem optimally and
bounded-suboptimally. We experimentally compare these algorithms on a variety
of different benchmark domains.
