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An embedding of a graph in $3$-space is linkless if for every two disjoint cycles there exists an embedded ball that contains one of the cycles and is disjoint from the other. We prove that every bipartite linklessly embeddable (simple)…

Combinatorics · Mathematics 2020-01-01 Rose McCarty , Robin Thomas

In a simple drawing of a graph every pair of edges intersect each other in at most one point, which is either a common endvertex or a proper crossing. For each positive integer $n$, Negami identified a drawing $B_n$ of the complete…

Combinatorics · Mathematics 2025-09-26 Jozsef Balogh , Irene Parada , Gelasio Salazar

In this paper, firstly, we provide some necessary and sufficient conditions for generalized Cayley graphs on abelian groups to be bipartite. Secondly, we deduce several necessary and sufficient conditions for generalized Cayley graphs on…

Combinatorics · Mathematics 2024-12-18 Liao Qianfen , Liu Weijun , Zhang Pengli

Given a finite group G, let cd(G) denote the set of degrees of the irreducible complex characters of G. The character degree graph of G is defined as the simple undirected graph whose vertices are the prime divisors of the numbers in cd(G),…

Group Theory · Mathematics 2018-09-28 Zeinab Akhlaghi , Carlo Casolo , Silvio Dolfi , Emanuele Pacifici , Lucia Sanus

This paper proposes an efficient method to construct the bipartite graph with as many edges as possible while without introducing the shortest cycles of length equal to 4. The binary matrix associated with the bipartite graph described…

Information Theory · Computer Science 2014-04-22 Weizhi Lu , Kidiyo Kpalma , Joseph Ronsin

In this work we study the null space of bipartite graphs without cycles of length multiple of $4$, and its relation to structural properties. We decompose them into two subgraphs: $C_N(G)$ and $C_S(G)$. $C_N(G)$ has perfect matching and its…

Combinatorics · Mathematics 2018-10-16 Daniel A. Jaume , Gonzalo Molina , Adrián Pastine

An edge-coloring of a graph $G$ with colors $1,...,t$ is called an interval $t$-coloring if all colors are used, and the colors of edges incident to any vertex of $G$ are distinct and form an interval of integers. In 1991 Erd\H{o}s…

Combinatorics · Mathematics 2013-01-21 Petros A. Petrosyan , Hrant H. Khachatrian

A graph is unichord free if it does not contain a cycle with exactly one chord as its subgraph. In [3], it is shown that a graph is unichord free if and only if every minimal vertex separator is a stable set. In this paper, we first show…

Discrete Mathematics · Computer Science 2014-10-27 Mahati Kumar , S. Manasvini , N. Sadagopan , Adithya Seshadri

Let $R$ be a ring (not necessary commutative) with non-zero identity. The unit graph of $R$, denoted by $G(R)$, is a graph with elements of $R$ as its vertices and two distinct vertices $a$ and $b$ are adjacent if and only if $a+b$ is a…

Rings and Algebras · Mathematics 2016-04-20 S. Akbari , E. Estaji , M. R. Khorsandi

In this paper, we deal with the signed bad number and the negative decision number of graphs. We show that two upper bounds concerning these two parameters for bipartite graphs in papers [Discrete Math. Algorithms Appl. 1 (2011), 33--41]…

Combinatorics · Mathematics 2021-02-02 Doost Ali Mojdeh , Babak Samadi

It was recently shown \cite{STV} that satisfiability is polynomially solvable when the incidence graph is an interval bipartite graph (an interval graph turned into a bipartite graph by omitting all edges within each partite set). Here we…

Data Structures and Algorithms · Computer Science 2016-02-26 Serge Gaspers , Christos Papadimitriou , Sigve Hortemo Saether , Jan Arne Telle

A bipartite graph is called bipancyclic if it contains cycles of every even length from four up to the number of vertices in the graph. A theorem of Schmeichel and Mitchem states that for $n \geq 4$, every balanced bipartite graph on $2n$…

Combinatorics · Mathematics 2021-01-26 Peter Bradshaw

The Near-Bipartiteness problem is that of deciding whether or not the vertices of a graph can be partitioned into sets $A$ and $B$, where $A$ is an independent set and $B$ induces a forest. The set $A$ in such a partition is said to be an…

Data Structures and Algorithms · Computer Science 2017-08-01 Marthe Bonamy , Konrad K. Dabrowski , Carl Feghali , Matthew Johnson , Daniel Paulusma

We use a tensor unfolding technique to prove a new identifiability result for discrete bipartite graphical models, which have a bipartite graph between an observed and a latent layer. This model family includes popular models such as…

Statistics Theory · Mathematics 2025-01-22 Yuqi Gu

A graph $G$ is $\alpha$-excellent if every vertex of $G$ is contained in some maximum independent set of $G$. In this paper, we characterize $\alpha$-excellent bipartite graphs, $\alpha$-excellent unicyclic graphs, $\alpha$-excellent…

Combinatorics · Mathematics 2022-08-19 M. Dettlaff , M. A. Henning , J. Topp

This paper studies the problem of upper bounding the number of independent sets in a graph, expressed in terms of its degree distribution. For bipartite regular graphs, Kahn (2001) established a tight upper bound using an…

Combinatorics · Mathematics 2021-04-01 Igal Sason

Bipartite graph embedding has recently attracted much attention due to the fact that bipartite graphs are widely used in various application domains. Most previous methods, which adopt random walk-based or reconstruction-based objectives,…

Social and Information Networks · Computer Science 2020-12-11 Jiangxia Cao , Xixun Lin , Shu Guo , Luchen Liu , Tingwen Liu , Bin Wang

We derive a formula for the QE constant of a complete multipartite graph and determine the complete multipartite graphs of non-QE class, namely, those which do not admit quadratic embeddings in a Euclidean space. Moreover, the primary…

Combinatorics · Mathematics 2023-11-09 Nobuaki Obata

In this paper we consider module-composed graphs, i.e. graphs which can be defined by a sequence of one-vertex insertions v_1,...,v_n, such that the neighbourhood of vertex v_i, 2<= i<= n, forms a module (a homogeneous set) of the graph…

Data Structures and Algorithms · Computer Science 2007-07-23 Frank Gurski

As a partial answer to a question of Rao, a deterministic and customizable efficient algorithm is presented to test whether an arbitrary graphical degree sequence has a bipartite realization. The algorithm can be configured to run in…

Combinatorics · Mathematics 2019-08-20 Kai Wang