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The graph polynomial for the number of independent sets of size $k$ in a general undirected graph is shown to be equal to an elementary symmetric polynomial of the vertex monomials, which are determined by the edges incident at the…

Combinatorics · Mathematics 2023-12-12 R. L. Streit

Let G be a finite group acting orthogonally on a pair (S^d,\Gamma) where \Gamma is a finite, connected graph of genus g>1 embedded in the sphere S^d. The 3-dimensional case d=3 has recently been considered in a paper by C. Wang, S. Wang, Y.…

Geometric Topology · Mathematics 2017-06-19 Bruno P. Zimmermann

We prove that the `Upper Matching Conjecture' of Friedland, Krop, and Markstr\"om and the analogous conjecture of Kahn for independent sets in regular graphs hold for all large enough graphs as a function of the degree. That is, for every…

Combinatorics · Mathematics 2021-08-02 Ewan Davies , Matthew Jenssen , Will Perkins

Write ${\cal I}(G)$ for the set of independent sets of a graph $G$ and $i(G)$ for $|{\cal I}(G)|$. It has been conjectured (by Alon and Kahn) that for an $N$-vertex, $d$-regular graph $G$, $$ i(G) \leq \left(2^{d+1}-1\right)^{N/2d}. $$ If…

Combinatorics · Mathematics 2010-07-29 David Galvin

An ordered graph $G$ is a graph whose vertex set is a subset of integers. The edges are interpreted as tuples $(u,v)$ with $u < v$. For a positive integer $s$, a matrix $M \in \mathbb{Z}^{s \times 4}$, and a vector $\mathbf{p} =…

Combinatorics · Mathematics 2016-10-05 Maria Axenovich , Jonathan Rollin , Torsten Ueckerdt

Consider a graph on the non-singular matrices over a finite field, in which two distinct non-singular matrices are joined by an edge whenever their sum is singular. We prove an upper bound for the independence number of this graph. As a…

Combinatorics · Mathematics 2024-05-15 Bogdan Nica

In this paper, we study non-zero component graph $\Gamma(\mathbb{V})$ on a finite dimensional vector space $\mathbb{V}$ over a finite field $\mathbb{F}$. We show that the graph is Hamiltonian and not Eulerian. We also characterize the…

General Mathematics · Mathematics 2021-11-09 Angsuman Das

Motivated by the definition of linear coloring on simplicial complexes, recently introduced in the context of algebraic topology \cite{Civan}, and the framework through which it was studied, we introduce the linear coloring on graphs. We…

Discrete Mathematics · Computer Science 2008-07-29 Kyriaki Ioannidou , Stavros D. Nikolopoulos

A $k$-$\gamma_{c}$-edge critical graph is a graph $G$ with the connected domination number $\gamma_{c}(G) = k$ and $\gamma_{c}(G + uv) < k$ for every $uv \in E(\overline{G})$. Further, a $2$-connected graph $G$ is said to be…

Combinatorics · Mathematics 2022-08-19 Norah Almalki , Pawaton Kaemawichanurat

Let $d, n \in \mathbb{Z}^+$ such that $1\leq d \leq n$. A $d$-code $\mathcal{C} \subset \mathbb{F}_q^{n \times n}$ is a subset of order $n$ square matrices with the property that for all pairs of distinct elements in $\mathcal{C}$, the rank…

Combinatorics · Mathematics 2020-05-13 G. Longobardi , G. Lunardon , R. Trombetti , Y. Zhou

Transiso graph $\Gamma_d(G)$ is defined in for a finite group $G$ and a divisor $d$ of $|G|$. In the present paper, we have determined some finite groups $G$ for which the graphs $\Gamma_d(G)$ are complete for each divisor $d$ of $|G|$. We…

Group Theory · Mathematics 2016-12-19 Laxmi Kant Mishra , Brajesh Kumar Sharma

We introduce a two-parameter framework that refines several classical graph invariants by imposing higher-order constraints along bounded-length geodesics. For integers $k,d\ge1$, a vertex set is called $k,d$-independent if every shortest…

Combinatorics · Mathematics 2026-01-09 Brent Cody , Rose Detore

In this paper, we unify the Markov theory of a variety of different types of graphs used in graphical Markov models by introducing the class of loopless mixed graphs, and show that all independence models induced by $m$-separation on such…

Other Statistics · Statistics 2014-03-13 Kayvan Sadeghi , Steffen Lauritzen

A Gallai coloring of the complete graph is an edge-coloring with no rainbow triangle. This concept first appeared in the study of comparability graphs and anti-Ramsey theory. We introduce a transitive analogue for acyclic directed graphs,…

Combinatorics · Mathematics 2023-09-21 R. M. Adin , A. Berenstein , J. Greenstein , J. -R. Li , A. Marmor , Y. Roichman

Let $G$ be a graph of order $n$. It is well-known that $\alpha(G)\geq \sum_{i=1}^n \frac{1}{1+d_i}$, where $\alpha(G)$ is the independence number of $G$ and $d_1,\ldots,d_n$ is the degree sequence of $G$. We extend this result to digraphs…

Combinatorics · Mathematics 2017-11-20 Saeed Akbari , Amir Hossein Ghodrati , Afrouz Jabalameli , Morteza Saghafian

For an edge-colored graph $G$, we call an edge-cut $M$ of $G$ monochromatic if the edges of $M$ are colored with the same color. The graph $G$ is called monochromatic disconnected if any two distinct vertices of $G$ are separated by a…

Combinatorics · Mathematics 2020-09-07 Ping Li , Xueliang Li

The classical theorem of Vizing states that every graph of maximum degree $d$ admits an edge-coloring with at most $d+1$ colors. Furthermore, as it was earlier shown by K\H{o}nig, $d$ colors suffice if the graph is bipartite. We investigate…

Combinatorics · Mathematics 2016-08-23 Endre Csóka , Gabor Lippner , Oleg Pikhurko

Let $R$ be a noncommutative ring with identity. The commuting graph of $R$, denoted by $\Gamma(R)$, is a graph with vertex set $R \setminus Z(R)$, and two vertices $a$, $b$ are adjacent if $a\neq b$ and $ab=ba$. Let $T=Tr(R)$ be the ring of…

Rings and Algebras · Mathematics 2024-02-21 Hassan Cheraghpour , Nader M. Ghosseiri , Madineh Jafari , Farnaz Seyfpour

An (m,n)-colored mixed graph, or simply, an (m,n)-graph is a graph having m different types of arcs and n different types of edges. A homomorphism of an (m,n)-graph G to another (m,n)-graph H is a vertex mapping that preserves adjacency,…

Combinatorics · Mathematics 2022-01-07 Dipayan Chakraborty , Sandip Das , Soumen Nandi , Debdeep Roy , Sagnik Sen

The Grundy number of a graph $G$, denoted by $\Gamma(G)$, is the largest $k$ such that there exists a partition of $V(G)$, into $k$ independent sets $V_1,\ldots, V_k$ and every vertex of $V_i$ is adjacent to at least one vertex in $V_j$,…

Discrete Mathematics · Computer Science 2014-05-20 Nicolas Gastineau , Hamamache Kheddouci , Olivier Togni