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In extremal graph theory, the problem of finding the elements of a given class of graphs which contain the most cliques traces its routes back to Tur\'an's famous theorem. We consider the implications of the connectivity property of…

Combinatorics · Mathematics 2018-10-11 Corbin Groothuis

A hypergraph is a useful combinatorial object to model ternary or higher-order relations among entities. Clustering hypergraphs is a fundamental task in network analysis. In this study, we develop two clustering algorithms based on…

Data Structures and Algorithms · Computer Science 2021-10-27 Yuuki Takai , Atsushi Miyauchi , Masahiro Ikeda , Yuichi Yoshida

We prove that for $k \ll \sqrt[4]{n}$ regular resolution requires length $n^{\Omega(k)}$ to establish that an Erd\H{o}s-R\'enyi graph with appropriately chosen edge density does not contain a $k$-clique. This lower bound is optimal up to…

Computational Complexity · Computer Science 2020-12-18 Albert Atserias , Ilario Bonacina , Susanna F. de Rezende , Massimo Lauria , Jakob Nordström , Alexander Razborov

Bonne and Censor-Hillel (ICALP 2019) initiated the study of distributed subgraph finding in dynamic networks of limited bandwidth. For the case where the target subgraph is a clique, they determined the tight bandwidth complexity bounds in…

Data Structures and Algorithms · Computer Science 2025-08-25 Yi-Jun Chang , Lyuting Chen , Yanyu Chen , Gopinath Mishra , Mingyang Yang

We determine new upper bounds for the clique numbers of strongly regular graphs in terms of their parameters. These bounds improve on the Delsarte bound for infinitely many feasible parameter tuples for strongly regular graphs, including…

Combinatorics · Mathematics 2019-01-31 Gary R. W. Greaves , Leonard H. Soicher

A clique in an undirected graph G= (V, E) is a subset V' V of vertices, each pair of which is connected by an edge in E. The clique problem is an optimization problem of finding a clique of maximum size in graph. The clique problem is…

Discrete Mathematics · Computer Science 2007-10-04 Murali Krishna P , Sabu . M Thampi

This work derives an upper bound on the maximum cardinality of a family of graphs on a fixed number of vertices, in which the intersection of every two graphs in that family contains a subgraph that is isomorphic to a specified graph H.…

Combinatorics · Mathematics 2025-05-23 Igal Sason

We establish tight lower and upper bounds on the number of edges in traceable graphs in several classes of dense graphs. A graph is traceable if it has a Hamiltonian path. We show that the bound is: - quadratic for the class of graphs of…

Combinatorics · Mathematics 2025-09-03 Michal Dvořák , Dušan Knop , Michal Opler , Jan Pokorný , Ondřej Suchý , Krisztina Szilágyi

Finding the largest clique is a notoriously hard problem, even on random graphs. It is known that the clique number of a random graph G(n,1/2) is almost surely either k or k+1, where k = 2log n - 2log(log n) - 1. However, a simple greedy…

Data Structures and Algorithms · Computer Science 2008-09-22 Atish Das Sarma , Amit Deshpande , Ravi Kannan

Let $[n]$ denote the set $\{1, 2, \ldots, n\}$ and $\mathcal{F}^{(r)}_{n,k,a}$ be an $r$-uniform hypergraph on the vertex set $[n]$ with edge set consisting of all the $r$-element subsets of $[n]$ that contains at least $a$ vertices in…

Combinatorics · Mathematics 2020-10-27 Erica L. L. Liu , Jian Wang

Graphs whose maximum clique size exceeds half of the total number of vertices satisfy a classical property: the family of their maximum sized cliques can be pierced by a single vertex. This result dates back to a 1965 theorem by Hajnal.…

Combinatorics · Mathematics 2026-04-24 Andreas Holmsen , Attila Jung , Balázs Keszegh , Dániel G. Simon , Gábor Tardos

Motivated by very large-scale communication networks, we newly introduce exponentiation of graphs. Using the exponential operation on graphs, we can construct various graphs of multi-exponential order with logarithmic diameter. We show that…

Combinatorics · Mathematics 2025-01-28 Toru Hasunuma

In 1990 Bender, Canfield and McKay gave an asymptotic formula for the number of connected graphs on $[n]=\{1,2,\ldots,n\}$ with $m$ edges, whenever $n\to\infty$ and $n-1\le m=m(n)\le \binom{n}{2}$. We give an asymptotic formula for the…

Combinatorics · Mathematics 2018-11-05 Béla Bollobás , Oliver Riordan

Recently Cutler and Radcliffe proved that the graph on $n$ vertices with maximum degree at most $r$ having the most cliques is a disjoint union of $\lfloor n/(r+1)\rfloor$ cliques of size $r+1$ together with a clique on the remainder of the…

Combinatorics · Mathematics 2021-02-19 Rachel Kirsch , A. J. Radcliffe

We consider maximum packings of edge-disjoint $4$-cliques in the complete graph $K_n$. When $n \equiv 1$ or $4 \pmod{12}$, these are simply block designs. In other congruence classes, there are necessarily uncovered edges; we examine the…

Combinatorics · Mathematics 2019-05-30 Yanxun Chang , Peter J. Dukes , Tao Feng

In this paper, we provide upper and lower bounds on the crossing numbers of dense graphs on surfaces, which match up to constant factors. First, we prove that if $G$ is a dense enough graph with $m$ edges and $\Sigma$ is a surface of genus…

Combinatorics · Mathematics 2025-06-12 Alfredo Hubard , Arnaud de Mesmay , Hugo Parlier

In 1965 Erd\H{o}s conjectured that the number of edges in k-uniform hypergraphs on n vertices in which the largest matching has s edges is maximized for hypergraphs of one of two special types. We settled this conjecture in the affirmative…

Combinatorics · Mathematics 2019-03-12 Tomasz Luczak , Katarzyna Mieczkowska

Let $\Gamma(n,k)$ be the set of $2$-connected $n$-vertex graphs containing an edge that is not on any cycle of length at least $k+1.$ Let $g_s(n,k)$ denote the maximum number of $s$-cliques in a graph in $\Gamma(n,k).$ Recently, Ji and Ye…

Combinatorics · Mathematics 2023-09-13 Leilei Zhang

We present an exact algorithm for computing all common subgraphs with the maximum number of vertices across multiple graphs. Our approach is further extended to handle the connected Maximum Common Subgraph (MCS), identifying the largest…

Data Structures and Algorithms · Computer Science 2025-04-03 Johannes B. S. Petersen , Akbar Davoodi , Thomas Gärtner , Marc Hellmuth , Daniel Merkle

For each uniformity $k \geq 3$, we construct $k$-uniform linear hypergraphs $G$ with arbitrarily large maximum degree $\Delta$ whose independence polynomial $Z_G$ has a root $\lambda$ with $\lvert\lambda\rvert = O\left(\frac{\log…

Combinatorics · Mathematics 2025-07-02 Shengtong Zhang