منابع مشابه
On CCE graphs of doubly partial orders
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 graph of a doubly partial order does not...
متن کاملThe niche graphs of doubly partial orders
The competition graph of a doubly partial order is known to be an interval graph. The competition-common enemy graph of a doubly partial order is also known to be an interval graph unless it contains a cycle of length 4 as an induced subgraph. In this paper, we show that the niche graph of a doubly partial order is not necessarily an interval graph. In fact, we prove that, for each n ≥ 4, there...
متن کاملThe competition hypergraphs of doubly partial orders
Since Cho and Kim [2] had shown that the competition graph of a doubly partial order is an interval graph, it has been actively studied whether or not the same phenomenon occurs for other variants of competition graph and interesting results have been obtained. Continuing in the same spirit, we study the competition hypergraph, an interesting variant of competition graph, of a doubly partial or...
متن کاملThe phylogeny graphs of double partial orders
The competition graph of a doubly partial order is known to be an interval graph. The CCE graph and the niche graph of a doubly partial order are also known to be interval graphs if the graphs do not contain a cycle of length four and three as an induced subgraph, respectively. Phylogeny graphs are variant of competition graphs. The phylogeny graph P (D) of a digraph D is the (simple undirected...
متن کاملOn competition graphs of n-tuply partial orders
Studying competition graphs of interesting digraphs is a basic open problem in the study of competition graphs. In this context, Cho and Kim [1] studied competition graphs of doubly partial orders and gave a nice characterization of the competition graphs of doubly partial orders. In this paper, we extend their results to a general case, which turns out to be quite interesting. Especially, we t...
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ژورنال
عنوان ژورنال: Discrete Applied Mathematics
سال: 2007
ISSN: 0166-218X
DOI: 10.1016/j.dam.2006.09.013