Topological directions in Cops and Robbers

TL;DR

This survey explores the interplay between topological graph theory and the Cops and Robbers game, highlighting known results, conjectures, and open problems related to cop numbers on various surfaces and graph classes.

Contribution

It provides a comprehensive overview of topological aspects influencing cop numbers, including conjectures, results for different surfaces, and open questions in the field.

Findings

Schroeder's conjecture holds for planar and toroidal graphs.

Cop number bounds relate to the genus of the surface.

Open problems remain for higher genus graphs.

Abstract

We survey results at the intersection of topological graph theory and the game of Cops and Robbers, focusing on results, conjectures, and open problems for the cop number of a graph embedded on a surface. After a discussion on results for planar graphs, we consider graphs of higher genus. In 2001, Schroeder conjectured that if a graph has genus $g,$ then its cop number is at most $g + 3.$ While Schroeder's bound is known to hold for planar and toroidal graphs, the case for graphs with higher genus remains open. We consider the capture time of graphs on surfaces and examine results for embeddings of graphs on non-orientable surfaces. We present a conjecture by the second author, and in addition, we survey results for the lazy cop number, directed graphs, and Zombies and Survivors.