{ "id": "2405.13363", "version": "v1", "published": "2024-05-22T05:43:56.000Z", "updated": "2024-05-22T05:43:56.000Z", "title": "Competition-common enemy graphs of degree-bounded digraphs", "authors": [ "Myungho Choi", "Hojin Chu", "Suh-Ryung Kim" ], "categories": [ "math.CO" ], "abstract": "The competition-common enemy graph (CCE graph) of a digraph $D$ is the graph with the vertex set $V(D)$ and an edge $uv$ if and only if $u$ and $v$ have a common predator and a common prey in $D$. If each vertex of a digraph $D$ has indegree at most $i$ and outdegree at most $j$, then $D$ is called an $\\langle i,j \\rangle$ digraph. In this paper, we fully characterize the CCE graphs of $\\langle 2,2\\rangle$ digraphs. Then we investigate the CCE graphs of acyclic $\\langle 2,2 \\rangle$ digraphs, and prove that any CCE graph of an acyclic $\\langle 2,2 \\rangle$ digraph with at most seven components is interval, and the bound is sharp. While characterizing acyclic $\\langle 2,2 \\rangle$ digraphs that have interval graphs as their competition graphs, Hefner~{\\it et al}. (1991) initiated the study of competition graphs of degree-bounded digraphs. Recently, Lee~{\\em et al}. (2017) and Eoh and Kim (2021) studied phylogeny graphs of degree-bounded digraphs to extend their work.", "revisions": [ { "version": "v1", "updated": "2024-05-22T05:43:56.000Z" } ], "analyses": { "subjects": [ "05C20", "05C75" ], "keywords": [ "competition-common enemy graph", "degree-bounded digraphs", "cce graph", "competition graphs", "common predator" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }