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We introduce a modification of the Tur\'an density of ordered graphs and investigate this graph parameter.

Combinatorics · Mathematics 2025-01-14 Christian Reiher , Vojtěch Rödl , Marcelo Sales , Mathias Schacht

Given a graph G = (V,E), a vertex subset S is called t-stable (or t-dependent) if the subgraph G[S] induced on S has maximum degree at most t. The t-stability number of G is the maximum order of a t-stable set in G. We investigate the…

Combinatorics · Mathematics 2010-10-27 Nikolaos Fountoulakis , Ross J. Kang , Colin McDiarmid

We present a new sufficient condition on stability number and toughness of the graph to have an f-factor.

Discrete Mathematics · Computer Science 2010-11-03 Kouider Mekkia

The following sharpening of Tur\'an's theorem is proved. Let $T_{n,p}$ denote the complete $p$--partite graph of order $n$ having the maximum number of edges. If $G$ is an $n$-vertex $K_{p+1}$-free graph with $e(T_{n,p})-t$ edges then there…

Combinatorics · Mathematics 2015-01-14 Zoltán Füredi

For a family of graphs $\cal F$, a graph $G$ is $\cal F$-free if it does not contain a member of $\cal F$ as a subgraph. The Tur\'an number $\textrm{ex}(n,{\cal F})$ is the maximum number of edges in an $n$-vertex graph which is $\cal…

Combinatorics · Mathematics 2024-12-13 Chunyang Dou , Fu-tao Hu , Xing Peng

This paper introduces and studies the stability of the strong domination number of a graph, denoted $\operatorname{st}_{\gamma_{st}}(G)$, defined as the minimum number of vertices whose removal changes the strong domination number…

Combinatorics · Mathematics 2026-01-08 Saeid Alikhani , Mazharuddin Mehraban , Hossein Shojaaldini Ardakani

Graph parameters such as the clique number, the chromatic number, and the independence number are central in many areas, ranging from computer networks to linguistics to computational neuroscience to social networks. In particular, the…

Computational Complexity · Computer Science 2020-12-15 Fabian Frei , Edith Hemaspaandra , Jörg Rothe

Combinatorial batch codes provide a tool for distributed data storage, with the feature of keeping privacy during information retrieval. Recently, Balachandran and Bhattacharya observed that the problem of constructing such uniform codes in…

Combinatorics · Mathematics 2013-09-26 Csilla Bujtás , Zsolt Tuza

Frei et al. [6] showed that the problem to decide whether a graph is stable with respect to some graph parameter under adding or removing either edges or vertices is $\Theta_2^{\text{P}}$-complete. They studied the common graph parameters…

Computational Complexity · Computer Science 2021-06-04 Robin Weishaupt , Jörg Rothe

In this paper we study some properties of Fibonacci-sum set-graphs. The aforesaid graphs are an extension of the notion of Fibonacci-sum graphs to the notion of set-graphs. The colouring of Fibonacci-sum graphs is also discussed. A number…

General Mathematics · Mathematics 2018-02-08 Eunice G Mphako-Banda , Johan Kok , Sudev Naduvath

For a graph $H$, the {\em extremal number} $ex(n,H)$ is the maximum number of edges in a graph of order $n$ not containing a subgraph isomorphic to $H$. Let $\delta(H)>0$ and $\Delta(H)$ denote the minimum degree and maximum degree of $H$,…

Combinatorics · Mathematics 2014-04-07 Noga Alon , Raphael Yuster

A circular arc graph is the intersection graph of a collection of connected arcs on the circle. We solve a Tur'an-type problem for circular arc graphs: for n arcs, if m and M are the minimum and maximum number of arcs that contain a common…

Combinatorics · Mathematics 2011-10-20 Rosalie Carlson , Stephen Flood , Kevin O'Neill , Francis Edward Su

Let $I(F,n)$ denote the maximum number of induced copies of a graph $F$ in an $n$-vertex graph. The inducibility of $F$, defined as $i(F)=\lim_{n\to \infty} I(F,n)/\binom{n}{v(F)}$, is a central problem in extremal graph theory. In this…

Combinatorics · Mathematics 2026-01-23 Xizhi Liu , Jie Ma , Tianming Zhu

Tur\'an number is one of primary topics in the combinatorics of finite sets,in this paper, we will present a new upper bound for Tur\'an number.

Combinatorics · Mathematics 2011-10-25 An-Ping Li

For fixed graphs $H$ and $F$, the \emph{generalized Tur\'an number} $\mathrm{ex}(n,H,F)$ is the maximum possible number of copies of a subgraph $H$ in an $n$-vertex $F$-free graph. This article is a survey of this extremal function whose…

Combinatorics · Mathematics 2025-06-05 Dániel Gerbner , Cory Palmer

Let $\mathscr{F}$ be a family of graphs. A graph $G$ is $\mathscr{F}$-free if $G$ does not contain any $F\in \mathscr{F}$ as a subgraph. The Tur\'an number, denoted by $ex(n, \mathscr{F})$, is the maximum number of edges in an $n$-vertex…

Combinatorics · Mathematics 2025-07-16 Haixiang Zhang , Xiamiao Zhao , Mei Lu

Computer or communication networks are so designed that they do not easily get disrupted under external attack and, moreover, these are easily reconstructible if they do get disrupted. These desirable properties of networks can be measured…

Combinatorics · Mathematics 2011-09-23 T. C. E. Cheng , Yinkui Li , Chuandong Xu , Shenggui Zhang

Both the Simonovits stability theorem and the Nikiforov spectral stability theorem are powerful tools for solving exact values of Tur\'{a}n numbers in extremal graph theory. Recently, F\"{u}redi [J. Combin. Theory Ser. B 115 (2015)]…

Combinatorics · Mathematics 2022-03-08 Yongtao Li , Yuejian Peng

The stability number of a graph G is the cardinality of a stability system of G (that is of a stable set of maximum size of G). A graph is alpha-stable if its stability number remains the same upon both the deletion and the addition of any…

Combinatorics · Mathematics 2007-05-23 Vadim E. Levit , Eugen Mandrescu

We address a problem which is a generalization of Tur\'an-type problems recently introduced by Imolay, Karl, Nagy and V\'ali. Let $F$ be a fixed graph and let $G$ be the union of $k$ edge-disjoint copies of $F$, namely $G =…

Combinatorics · Mathematics 2024-06-21 József Balogh , Anita Liebenau , Letícia Mattos , Natasha Morrison