Enumeration and Maximum Number of Minimal Connected Vertex Covers in Graphs

Connected Vertex Cover is one of the classical problems of computer science, already mentioned in the monograph of Garey and Johnson [W.H. Freeman & Co., 1979]. Although the optimization and decision variants of finding connected vertex covers of minimum size or weight are well-studied, surprisingly there is no work on the enumeration or maximum number of minimal connected vertex covers of a graph. In this paper we show that the number of minimal connected vertex covers of a graph is at most 1.8668, and these sets can be enumerated in time O(1.8668). For graphs of chordality at most 5, we are able to give a better upper bound, and for chordal graphs and distance-hereditary graphs we are able to give tight bounds on the maximum number of minimal connected vertex covers.