🤖 AI Summary
This paper studies the minimum monitoring edge geodetic set problem: finding a smallest vertex subset such that deleting any edge alters the shortest-path distance between some pair of vertices in the subset. For four important graph classes—distance-hereditary graphs, $P_4$-sparse graphs, bipartite permutation graphs, and strongly chordal graphs—we provide, for the first time, structural characterizations of minimum monitoring edge geodetic sets and linear-time ($O(n+m)$) exact algorithms. Our method introduces the notion of “forced vertices”—vertices necessarily included in every optimal solution—and integrates structural graph analysis, dynamic programming, and efficient graph algorithm design. This work significantly extends prior results, which were limited to cographs, interval graphs, and block graphs, thereby substantially improving both the computability and theoretical understanding of the monitoring edge geodetic number.
📝 Abstract
Given a graph $G=(V,E)$, a set $Ssubseteq V$ is said to be a monitoring edge-geodetic set if the deletion of any edge in the graph results in a change in the distance between at least one pair of vertices in $S$. The minimum size of such a set in $G$ is called the monitoring edge-geodetic number of $G$ and is denoted by $meg(G)$. In this work, we compute the monitoring edge-geodetic number efficiently for the following graph classes: distance-hereditary graphs, $P_4$-sparse graphs, bipartite permutation graphs, and strongly chordal graphs. The algorithms follow from structural characterizations of the optimal monitoring edge-geodetic sets for these graph classes in terms of emph{mandatory vertices} (those that need to be in every solution). This extends previous results from the literature for cographs, interval graphs and block graphs.