The Snow Team Problem (Clearing Directed Subgraphs by Mobile Agents)

12/01/2017

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by   Dariusz Dereniowski, et al.

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We study several problems of clearing subgraphs by mobile agents in digraphs. The agents can move only along directed walks of a digraph and, depending on the variant, their initial positions may be pre-specified. In general, for a given subset S of vertices of a digraph D and a positive integer k, the objective is to determine whether there is a subgraph H=(V_H,A_H) of D such that (a) S⊆V_H, (b) H is the union of k directed walks in D, and (c) the underlying graph of H includes a Steiner tree for S in D. We provide several results on the polynomial time tractability, hardness, and parameterized complexity of the problem.