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The (n,k)-star graph is a very important computer modelling. The independent number and chromatic number of a graph are two important parameters in graph theory. However, we did not know the values of this two parameters of the (n,k)-star…

Combinatorics · Mathematics 2017-02-15 Fu-Tao Hu

Let $G$ be a $K_4$-free graph of order $n$ and let $k$ be an integer with $0\leq k\leq n$. We show the existence of positive constants $\eta$ and $\nu$ such that $G$ has at most $(4-\eta)^{(5-\eta)k-n}(5-\eta)^{n-(4-\eta)k}$ maximal…

Combinatorics · Mathematics 2025-12-23 Thilo Hartel , Lucas Picasarri-Arrieta , Dieter Rautenbach

We show that there are polynomial-time algorithms to compute maximum independent sets in the categorical products of two cographs and two splitgraphs. The ultimate categorical independence ratio of a graph G is defined as lim_{k --> infty}…

Discrete Mathematics · Computer Science 2013-06-10 Wing-Kai Hon , Ton Kloks , Hsiang-Hsuan Liu , Sheung-Hung Poon , Yue-Li Wang

A connected set in a graph is a subset of vertices whose induced subgraph is connected. Although counting the number of connected sets in a graph is generally a \#P-complete problem, it remains an active area of research. In 2020, Vince…

Combinatorics · Mathematics 2025-04-04 Hongxia Ma , Xian'an Jin , Weiling Yang , Meiqiao Zhang

An independent set $I_c$ is a \textit{critical independent set} if $|I_c| - |N(I_c)| \geq |J| - |N(J)|$, for any independent set $J$. The \textit{critical independence number} of a graph is the cardinality of a maximum critical independent…

Combinatorics · Mathematics 2009-12-14 Craig Eric Larson

A theorem of Ding, Oporowski, Oxley, and Vertigan implies that any sufficiently large twin-free graph contains a large matching, a co-matching, or a half-graph as a semi-induced subgraph. The sizes of these unavoidable patterns are measured…

Computational Complexity · Computer Science 2026-02-10 Jan Dreier , Nikolas Mählmann , Sebastian Siebertz

The Maximum Weight Independent Set (MWIS) Problem on graphs with vertex weights asks for a set of pairwise nonadjacent vertices of maximum total weight. Being one of the most investigated and most important problems on graphs, it is well…

Discrete Mathematics · Computer Science 2012-09-13 Andreas Brandstädt , Raffaele Mosca

We review the progress made on bounding the number of independent sets in $d$-regular and irregular graphs over the last 31 years. We particularly focus on contributions from Kahn, Zhao, and Sah et al. in incrementally proving stronger and…

Combinatorics · Mathematics 2024-05-31 Dev Chheda , Ram Goel , Eddie Qiao

Computing maximum weight independent sets in graphs is an important NP-hard optimization problem. The problem is particularly difficult to solve in large graphs for which data reduction techniques do not work well. To be more precise,…

Data Structures and Algorithms · Computer Science 2023-04-24 Ernestine Großmann , Sebastian Lamm , Christian Schulz , Darren Strash

A new method of abstracting the independent gauge invariances of higher derivative systems, recently introduced in [1], has been applied to higher derivative field theories. This has been discussed taking the extended Maxwell-Chern-Simons…

High Energy Physics - Theory · Physics 2015-06-03 Pradip Mukherjee , Biswajit Paul

Chandrasekaran, Chertkov, Gamarnik, Shah, and Shin recently proved that the average number of independent sets of random regular graphs of size n and degree 3 approaches w^n for large n, where w is approximately 1.54563, consistent with the…

Discrete Mathematics · Computer Science 2009-10-27 Adam B. Yedidia

Kir\'{a}ly in [On maximal independent arborescence packing, SIAM J. Discrete. Math. 30 (4) (2016), 2107-2114] solved the following packing problem: Given a digraph $D = (V, A)$, a matroid $M$ on a set $S = \{s_{1}, \ldots,s_{k} \}$ along…

Combinatorics · Mathematics 2021-03-09 Hui Gao , Daqing Yang

Amongst $d$-regular $r$-uniform hypergraphs on $n$ vertices, which ones have the largest number of independent sets? While the analogous problem for graphs (originally raised by Granville) is now well-understood, it is not even clear what…

Combinatorics · Mathematics 2020-02-25 Jozsef Balogh , Bela Bollobas , Bhargav Narayanan

In this paper we study the Betti numbers of Stanley-Reisner ideals generated in degree 2. We show that the first six Betti numbers do not depend on the characteristic of the ground field. We also show that, if the number of variables $n$ is…

Commutative Algebra · Mathematics 2007-05-23 Mordechai Katzman

A potted graph is a unicyclic graph such that its cycle contains a unique vertex with degree larger than 2. Given a graph $G$, a subset of $V(G)$ is a dissociation set of $G$ if it induces a subgraph with maximum degree at most one. A…

Combinatorics · Mathematics 2024-02-06 Zejun Huang , Xinwei Zhang

We describe an infinite family of graphs $G_n$, where $G_n$ has $n$ vertices, independence number at least $n/4$, and no set of less than $\sqrt{n}/2$ vertices intersects all its maximum independent sets. This is motivated by a question of…

Combinatorics · Mathematics 2021-04-06 Noga Alon

The residue of a graph is the number of zeros left after iteratively applying the Havel-Hakimi algorithm to its degree sequence. Favaron, Mah\'{e}o, and Sacl\'{e} showed that the residue is a lower bound on the independence number. The…

Combinatorics · Mathematics 2019-10-15 Benjamin Lantz

We give a very short and simple proof of Zykov's generalization of Tur\'{a}n's theorem, which implies that the number of maximum independent sets of a graph of order $n$ and independence number $\alpha$ with $\alpha<n$ is at most…

Combinatorics · Mathematics 2018-05-08 Elena Mohr , Dieter Rautenbach

Let $k\ge 2$ be an integer and $T_1,\ldots, T_k$ be spanning trees of a graph $G$. If for any pair of vertices $(u,v)$ of $V(G)$, the paths from $u$ to $v$ in each $T_i$, $1\le i\le k$, do not contain common edges and common vertices,…

Discrete Mathematics · Computer Science 2014-09-23 Benoit Darties , Nicolas Gastineau , Olivier Togni

We study probabilistic cellular automata (PCA) and quantum cellular automata (QCA) as frameworks for solving the Maximum Independent Set (MIS) problem. We first introduce a synchronous PCA whose dynamics drives the system toward the…

Quantum Physics · Physics 2025-12-09 Federico Dell'Anna , Matteo Grotti , Vito Giardinelli