Mutual-visibility sets in Cartesian products of paths and cycles

Abstract

For a given graph $G$, the mutual-visibility problem asks for the largest set of vertices $M\subseteq V(G)$ with the property that for any pair of vertices $u,v\in M$ there exists a shortest $u,v$-path of $G$ that does not pass through any other vertex in $M$. The mutual-visibility problem for Cartesian products of a cycle and a path, as well as for Cartesian products of two cycles, is considered. Optimal solutions are provided for the majority of Cartesian products of a cycle and a path, while for the other family of graphs, the problem is completely solved.