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In this paper, we study the competition graphs of $d$-partial orders and obtain their characterization which extends results given by Cho and Kim \cite{chokim} in 2005. We also show that any graph can be made into the competition graph of a…

Combinatorics · Mathematics 2016-01-11 Jihoon Choi , Kyeong Seok Kim , Suh-Ryung Kim , Jung Yeun Lee , Yoshio Sano

In this paper, we study the competition graphs of $d$-partial orders and obtain their characterization which extends results given by Cho and Kim \cite{chokim} in 2005. We also show that any graph can be made into the competition graph of a…

Combinatorics · Mathematics 2016-01-11 Jihoon Choi , Kyeong Seok Kim , Suh-Ryung Kim , Jung Yeun Lee , Yoshio Sano

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…

Combinatorics · Mathematics 2010-06-01 Suh-Ryung Kim , Jung Yeun Lee , Boram Park , Won Jin Park , Yoshio Sano

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…

Combinatorics · Mathematics 2013-10-24 Boram Park , Yoshio Sano

Choi {\it et al.} [{J.~Choi, K.~S.~Kim, S.~-R.~Kim, J.~Y.~Lee, and Y.~Sano}: {On the competition graphs of $d$-partial orders}, \emph{Discrete Applied Mathematics} (2015), \texttt{http://dx.doi.org/10.1016/j.dam.2015.11.004}] introduced the…

Combinatorics · Mathematics 2016-01-11 Jihoon Choi , Suh-Ryung Kim , Jung Yeun Lee , Yoshio Sano

Choi {\it et al.} [{J.~Choi, K.~S.~Kim, S.~-R.~Kim, J.~Y.~Lee, and Y.~Sano}: {On the competition graphs of $d$-partial orders}, \emph{Discrete Applied Mathematics} (2015), \texttt{http://dx.doi.org/10.1016/j.dam.2015.11.004}] introduced the…

Combinatorics · Mathematics 2016-01-13 Jihoon Choi , Suh-Ryung Kim , Jung Yeun Lee , Yoshio Sano

In prior work, Cho and Kim studied competition graphs arising from doubly partial orders. In this article, we consider a related problem where competition graphs are instead induced by permutations. We first show that this approach produces…

Combinatorics · Mathematics 2015-03-20 Brian Nakamura , Elizabeth Yang

The competition graph of a directed acyclic graph D is the undirected graph on the same vertex set as D in which two distinct vertices are adjacent if they have a common out-neighbor in D. The competition number of an undirected graph G is…

Combinatorics · Mathematics 2013-10-24 Brendan D. McKay , Pascal Schweitzer , Patrick Schweitzer

In this paper, we use the Erd\"{o}s-Szekeres lemma to show that there exists a graph with partial order competition dimension greater than five.

Combinatorics · Mathematics 2018-10-15 Jihoon Choi , Soogang Eoh , Suh-Ryung Kim

In this article, we introduce the notion of the double competition multigraph of a digraph. We give characterizations of the double competition multigraphs of arbitrary digraphs, loopless digraphs, reflexive digraphs, and acyclic digraphs…

Combinatorics · Mathematics 2016-02-02 Jeongmi Park , Yoshio Sano

A linear-interval order is the intersection of a linear order and an interval order. For this class of orders, several structural results have been known. This paper introduces a new subclass of linear-interval orders. We call a partial…

Discrete Mathematics · Computer Science 2021-05-11 Asahi Takaoka

We say that a digraph $D$ is competitive if any pair of vertices has a common out-neighbor in $D$ and that a graph $G$ is competitively orientable if there exists a competitive orientation of $G$. The notion of competitive digraphs arose…

Combinatorics · Mathematics 2022-12-13 Myungho Choi , Minki Kwak , Suh-Ryung Kim

Let D be an acyclic digraph. The competition graph of D is a graph which has the same vertex set as D and has an edge between x and y if and only if there exists a vertex v in D such that (x,v) and (y,v) are arcs of D. For any graph G, G…

Combinatorics · Mathematics 2010-10-07 Jung Yeun Lee , Suh-Ryung Kim , Seog-Jin Kim , Yoshio Sano

An interval $k$-graph is the intersection graph of a family $\mathcal{I}$ of intervals of the real line partitioned into at most $k$ classes with vertices adjacent if and only if their corresponding intervals intersect and belong to…

Combinatorics · Mathematics 2016-03-01 David E. Brown , Breeann M. Flesch , Larry J. Langley

We say that a digraph $D$ is $(i,j)$-step competitive if any two vertices have an $(i,j)$-step common out-neighbor in $D$ and that a graph $G$ is $(i,j)$-step competitively orientable if there exists an $(i,j)$-step competitive orientation…

Combinatorics · Mathematics 2024-10-08 Myungho Choi , Suh-Ryung Kim

The competition graph of a digraph $D$ is a (simple undirected) graph which has the same vertex set as $D$ and has an edge between two distinct vertices $x$ and $y$ if and only if there exists a vertex $v$ in $D$ such that $(x,v)$ and…

Combinatorics · Mathematics 2013-12-25 Suh-Ryung Kim , Jung Yeun Lee , Boram Park , Yoshio Sano

The competition graph of a digraph D is a graph which has the same vertex set as D and has an edge between x and y if and only if there exists a vertex v in D such that (x,v) and (y,v) are arcs of D. For any graph G, G together with…

Combinatorics · Mathematics 2011-06-27 Boram Park , Yoshio Sano

We survey partial geometric designs and investigate their concurrences of points. The concurrence matrix of a design, which encodes the concurrences of pairs of points, can be used in the classification of designs in some extent. An…

Combinatorics · Mathematics 2022-01-04 Sung-Yell Song , Theodore Tranel

The niche graph of a digraph $D$ is the (simple undirected) graph which has the same vertex set as $D$ and has an edge between two distinct vertices $x$ and $y$ if and only if $N^+_D(x) \cap N^+_D(y) \neq \emptyset$ or $N^-_D(x) \cap…

Combinatorics · Mathematics 2014-08-12 Jeongmi Park , Yoshio Sano

The competition graph of a digraph D is a (simple undirected) graph which has the same vertex set as D and has an edge between x and y if and only if there exists a vertex v in D such that (x,v) and (y,v) are arcs of D. For any graph G, G…

Combinatorics · Mathematics 2011-11-14 Suh-Ryung Kim , Jung Yeun Lee , Boram Park , Yoshio Sano
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