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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

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

Since Cho and Kim (2005) showed 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…

Combinatorics · Mathematics 2015-03-19 Suh-Ryung Kim , Jung Yeun Lee , Boram Park , Yoshio Sano

We study subclasses of grid intersection graphs from the perspective of order dimension. We show that partial orders of height two whose comparability graph is a grid intersection graph have order dimension at most four. Starting from this…

Combinatorics · Mathematics 2015-12-09 Steven Chaplick , Stefan Felsner , Udo Hoffmann , Veit Wiechert

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

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

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

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

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 2011-03-01 Jung Yeun Lee , Suh-Ryung Kim , Yoshio Sano

A split graph is a graph whose vertex set can be partitioned into a clique and an independent set. A split comparability graph is a split graph which is transitively orientable. In this work, we characterize split comparability graphs in…

Combinatorics · Mathematics 2025-04-29 Tithi Dwary , Khyodeno Mozhui , K. V. Krishna

The Erd\H{o}s-Szekeres Theorem stated in terms of graphs says that any red-blue coloring of the edges of the ordered complete graph $K_{rs+1}$ contains a red copy of the monotone increasing path with $r$ edges or a blue copy of the monotone…

Combinatorics · Mathematics 2021-09-22 József Balogh , Felix Christian Clemen , Emily Heath , Mikhail Lavrov

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

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

A consequence of Ore's classic theorem characterizing the maximal graphs with given order and diameter is a determination of the largest such graphs. We give a very short and simple proof of this smaller result, based on a well-known…

Combinatorics · Mathematics 2018-11-14 Pu Qiao , Xingzhi Zhan

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

Half graphs and their variants, such as ladders, semi-ladders and co-matchings, are combinatorial objects that encode total orders in graphs. Works by Adler and Adler (Eur. J. Comb.; 2014) and Fabia\'nski et al. (STACS; 2019) prove that in…

Combinatorics · Mathematics 2021-03-11 Marek Sokołowski

We prove the following result: If $G$ be a connected graph on $n \ge 6$ vertices, then there exists a set of vertices $D$ with $|D| \le \frac{n}{3}$ and such that $V(G) \setminus N[D]$ is an independent set, where $N[D]$ is the closed…

Combinatorics · Mathematics 2015-05-01 Yair Caro , Adriana Hansberg

The competition number k(G) of a graph G is the smallest number k such that G together with k isolated vertices added is the competition graph of an acyclic digraph. A chordless cycle of length at least 4 of a graph is called a hole of the…

Combinatorics · Mathematics 2011-05-17 Jung Yeun Lee , Suh-Ryung Kim , Seog-Jin Kim , Yoshio Sano
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