ACYCLIC DIGRAPHS WHOSE 2-STEP COMPETITION GRAPHS ARE P$P_n\cup\ I_2$
Han-Hyun Cho, Suh-Ryung Kim, Yunsun Nam · Bulletin of the Korean Mathematical Society · 2000
The 2-step competition graph of D has the same vertex set as D and an edge between vertices x and y if and only if there exist (x, z)-walk of length 2 and (y, z)-walk of length 2 for some vertex z in D. The 2-step competition number of a graph G is the smallest number k such that G together with k isolated vertices is the 2-step competition graph of an acyclic digraph. Cho, et al. showed that the 2-step competition number of a path of length at least two is two. In this paper, we characterize all the minimal acyclic digraphs whose 2-step competition graphs are paths of length n with two isolated vertices and construct all such digraphs.