The One-Cop-Moves Game on Graphs of Small Treewidth

Abstract

This paper considers the one-cop-moves game played on a graph. In this game, a set of cops and a robber occupy the vertices of the graph and move alternately along the graph’s edges with perfect information about each other’s positions. The goal of the cops is to capture the robber. At cops’ turns, exactly one cop is allowed to move from his location to an adjacent vertex; at robber’s turns, she is allowed to move from her location to an adjacent vertex or to stay still. We want to find the minimum number of cops to capture the robber. This number is known as the cop number. In this paper, we investigate the cop number of several classes of graphs, including graphs with treewidth at most 2, Halin graphs, and Cartesian product graphs. We also give a characterization of k-winnable graphs in the one-cop-moves game.