Suh-Ryung Kim

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Let D be an acyclic digraph. The competition graph of D has the same set of vertices as D and an edge between vertices u and v if and only if there is a vertex x in D such that (u, x) and (v, x) are arcs of D. In this paper, we show that the competition graphs of doubly partial orders are interval graphs. We also show that an interval graph together with(More)
Let D be a digraph. The competition-common enemy graph (CCE graph) of D has the same set of vertices as D and an edge between vertices u and v if and only if there are vertices w and x in D such that (w, u), (w, v), (u, x), and (v, x) are arcs of D. We call a graph a CCE graph if it is the CCE graph of some digraph. In this paper, we show that if the CCE(More)
The competition graph of a digraph was introduced by Cohen in 1968 associated with the study of ecosystems. Since then, the competition graph has been widely studied and many variations have been introduced. In this paper, we de ne and study the m-step competition graph of a digraph which is another generalization of competition graph. ? 2000 Elsevier(More)
Given a digraph D, its competition graph has the same vertex set and an edge between two vertices x and y if there is a vertex u so that (x, u) and (y, u) are arcs of D. Motivated by a problem of communications, we study the competition graphs of the special digraphs known as semiorders. This leads us to define a conditions on digraphs called C(p) and C(p)(More)