Computer Science Journal of Moldova (Sep 2020)
On the Computational Complexity of Optimization Convex Covering Problems of Graphs
Abstract
In this paper we present further studies of convex covers and convex partitions of graphs. Let $G$ be a finite simple graph. A set of vertices $S$ of $G$ is convex if all vertices lying on a shortest path between any pair of vertices of $S$ are in $S$. If $3\leq|S|\leq|X|-1$, then $S$ is a nontrivial set. We prove that determining the minimum number of convex sets and the minimum number of nontrivial convex sets, which cover or partition a graph, is in general NP-hard. We also prove that it is NP-hard to determine the maximum number of nontrivial convex sets, which cover or partition a graph.