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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

We define a notion of (one-sided) shift spaces over infinite alphabets. Unlike many previous approaches to shift spaces over countable alphabets, our shift spaces are compact Hausdorff spaces. We examine shift morphisms between these shift…

Operator Algebras · Mathematics 2013-07-03 William Ott , Mark Tomforde , Paulette Willis

Given a graph $G$, we determine the structure of the rotation graph of a graph obtained by applying certain operations to $G$. Specifically, we consider the operations of adding a simplicial vertex, adding a true twin to a vertex, and the…

Combinatorics · Mathematics 2024-10-11 Ana Gargantini , Adrián Pastine , Pablo Torres

This paper is a survey on Extremal Graph Theory, primarily focusing on the case when one of the excluded graphs is bipartite. On one hand we give an introduction to this field and also describe many important results, methods, problems, and…

Combinatorics · Mathematics 2013-07-02 Zoltán Füredi , Miklós Simonovits

Let $G$ be a graph of order $n$ and let $k\in \{1,2,\ldots,n-1\}$. The $k$-token graph of $G$ is the graph, whose vertices are all the $k$-subsets of vertices of $G$, where two such $k$-sets are adjacent whenever their symmetric difference…

Combinatorics · Mathematics 2025-03-14 Ruy Fabila-Monroy , Ana Laura Trujillo-Negrete

A graph is said to be nearly complete bipartite if it can be obtained by deleting a set of independent edges from a complete bipartite graph. The nonorientable genus of such graphs is known except in a few cases where the sizes of the…

Combinatorics · Mathematics 2023-05-24 Warren Singh , Timothy Sun

We study algebraic shifting of uniform hypergraphs and finite simplicial complexes in the exterior algebra with respect to matrices which are not necessarily generic. Several questions raised by Kalai (2002) are addressed. For instance, it…

Combinatorics · Mathematics 2025-05-12 Antony Della Vecchia , Michael Joswig , Fabian Lenzen

It is known that the canonical double cover of any connected nonbipartite graph have an automorphism group of the form $H \rtimes \mathbb{Z}_2$, where $H$ is the set of automorphism which preserve bipartite parts. We construct connected…

Combinatorics · Mathematics 2024-06-11 Bartłomiej Bychawski

In \cite{Chan95}, the authors classified the 2-extendable abelian Cayley graphs and posed the problem of characterizing all 2-extendable Cayley graphs. We first show that a connected bipartite Cayley (vertex-transitive) graph is…

Combinatorics · Mathematics 2016-12-12 Qiuli Li , Xing Gao

Extending the work of Godsil and others, we investigate the notion of the inverse of a graph (specifically, of bipartite graphs with a unique perfect matching). We provide a concise necessary and sufficient condition for the invertibility…

Combinatorics · Mathematics 2011-08-19 Cam McLeman , Erin McNicholas

In this paper, we propose a characterization of chordal bipartite graphs and an efficient enumeration algorithm for chordal bipartite induced subgraphs. A chordal bipartite graph is a bipartite graph without induced cycles with length six…

Data Structures and Algorithms · Computer Science 2020-09-23 Kazuhiro Kurita , Kunihiro Wasa , Hiroki Arimura , Takeaki Uno

A bipartite graph is chordal bipartite if every cycle of length at least six contains a chord. We determine the minimum size in 2-connected chordal bipartite graphs with given order.

Combinatorics · Mathematics 2024-10-29 Licheng Zhang , Yuanqiu Huang

It is well known that a graph $G$ has a symmetric spectrum if and only if it is bipartite, a signed graph $\Gamma=(G,\sigma)$ has a symmetric spectrum if $G$ is bipartite. However, there exists a spectrally symmetric signed graph…

Combinatorics · Mathematics 2025-05-02 Deqiong Li , Qiongxiang Huang

Let G = G(V,E) be a graph with | V | vertices and | E | edges and total graph, T(G) is obtained from G. In This paper we have study the Harmonic index of total graph for standards graphs, bipartite graph of particular type, regular graph,…

Combinatorics · Mathematics 2017-08-09 Anandkumar Velusamy , Radha Rajamani Iyer

For positive integers $s,t,u,v$, we define a bipartite graph $\Gamma_{\mathbb{R}}(X^s Y^t,X^u Y^v)$ where each partite set is a copy of $\mathbb{R}^3$, and a vertex $(a_1,a_2,a_3)$ in the first partite set is adjacent to a vertex…

Combinatorics · Mathematics 2021-01-26 Alex Kodess , Brian G. Kronenthal , Diego Manzano-Ruiz , Ethan Noe

Let $k$ and $l$ be integers, both at least 2. A $(k,l)$-bipartite graph is an $l$-regular bipartite multigraph with coloured bipartite sets of size $k$. Define $\chi(k,l)$ and $\mu(k,l)$ to be the minimum and maximum order of automorphism…

Combinatorics · Mathematics 2025-10-06 Peter J. Cameron , Coen del Valle , Colva M. Roney-Dougal

The permanental polynomial of a graph $G$ is $\pi(G,x)\triangleq\mathrm{per}(xI-A(G))$. From the result that a bipartite graph $G$ admits an orientation $G^e$ such that every cycle is oddly oriented if and only if it contains no even…

Combinatorics · Mathematics 2010-10-07 Heping Zhang , Wei Li

In this paper we determine all the bipartite graphs with the maximum sum of squares of degrees among the ones with a given number of vertices and edges.

Combinatorics · Mathematics 2011-09-23 Shenggui Zhang , Chuncao Zhou

Connectedness and bipartiteness are basic properties of classical graphs, and the purpose of this paper is to investigate the case of quantum graphs. We introduce the notion of connectedness and bipartiteness of quantum graphs in terms of…

Operator Algebras · Mathematics 2024-07-31 Junichiro Matsuda

In [{Structural properties and decomposition of linear balanced matrices}, {\it Mathematical Programming}, 55:129--168, 1992], Conforti and Rao conjectured that every balanced bipartite graph contains an edge that is not the unique chord of…