On monophonic position sets of Cartesian and lexicographic products of graphs

The general position problem in graph theory asks for the number of vertices in a largest set $S$ of vertices of a graph $G$ such that no shortest path of $G$ contains more than two vertices of $S$. The analogous monophonic position problem is obtained from the general position problem by replacing ``shortest path" by ``induced path." This paper studies monophonic position sets in the Cartesian and lexicographic products of graphs. Sharp lower and upper bounds for the monophonic position number of Cartesian products are established, along with several exact values. For the lexicographic product, the monophonic position number is determined for arbitrary graphs.