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There is a remarkable connection between the maximum clique number and the Lagrangian of a graph given by T. S. Motzkin and E.G. Straus in 1965. This connection and its extensions were successfully employed in optimization to provide…

Combinatorics · Mathematics 2014-04-03 Yuejian Peng , Hegui Zhu , Yanling Zheng , Cheng Zhao

A remarkable connection between the order of a maximum clique and the Lagrangian of a graph was established by Motzkin and Straus in [7]. This connection and its extensions were successfully employed in optimization to provide heuristics…

Combinatorics · Mathematics 2012-12-13 Yuejian Peng , Qingsong Tang , Cheng Zhao

Motzkin and Straus established a close connection between the maximum clique problem and a solution (namely graph-Lagrangians) to the maximum value of a class of homogeneous quadratic multilinear functions over the standard simplex of the…

Combinatorics · Mathematics 2013-12-30 Qingsong Tang , Yuejian Peng , Xiangde Zhang , Cheng Zhao

There is a remarkable connection between the clique number and the Lagrangian of a 2-graph proved by Motzkin and Straus in 1965. It is useful in practice if similar results hold for hypergraphs. However the obvious generalization of Motzkin…

Combinatorics · Mathematics 2013-12-31 Qingsong Tang , Yuejian Peng , Xiangde Zhang , Cheng Zhao

A remarkable connection between the order of a maximum clique and the Graph-Lagrangian of a graph was established by Motzkin and Straus in 1965. This connection and its extension were useful in both combinatorics and optimization. Since…

Combinatorics · Mathematics 2014-05-27 Yuejian Peng , Yuping Yao

It is conjectured by Frankl and F\"uredi that the $r$-uniform hypergraph with $m$ edges formed by taking the first $m$ sets in the colex ordering of ${\mathbb N}^{(r)}$ has the largest Lagrangian of all $r$-uniform hypergraphs with $m$…

Combinatorics · Mathematics 2014-05-13 Qingsong Tang , Xiaojun Lu , Xiangde Zhang , Cheng Zhao

A remarkable connection between the order of a maximum clique and the Lagrangian of a graph was established by Motzkin and Straus in 1965. This connection and its extensions were applied in Tur\'{a}n problems of graphs and uniform…

Combinatorics · Mathematics 2013-11-01 Ran Gu , Xueliang Li , Yuejian Peng , Yongtang Shi

In 1965, Motzkin and Straus [5] provided a new proof of Turan's theorem based on a continuous characterization of the clique number of a graph using the Lagrangian of a graph. This new proof aroused interests in the study of Lagrangians of…

Combinatorics · Mathematics 2012-12-03 Qingsong Tang , Yuejian Peng , Xiangde Zhang , Cheng Zhao

In 1965, Motzkin and Straus established a remarkable connection between the order of a maximum clique and the Lagrangian of a graph and provided a new proof of Tur\'an's theorem using the connection. The connection of Lagrangians and…

Combinatorics · Mathematics 2013-12-17 Yuejian Peng , Hao Peng , Qingsong Tang , Cheng Zhao

The Lagrangian of a hypergraph has been a useful tool in hypergraph extremal problems. In most applications, we need an upper bound for the Lagrangian of a hypergraph. Frankl and Furedi in \cite{FF} conjectured that the $r$-graph with $m$…

Combinatorics · Mathematics 2014-02-18 Qingsong Tang , Hao Peng , Cailing Wang , Yuejian Peng

Frankl and F\"uredi (1989) conjectured that the $r$-graph with $m$ edges formed by taking the first $m$ sets in the colex ordering of ${\mathbb N}^{(r)}$ has the largest graph-Lagrangian of all $r$-graphs with $m$ edges. In this paper, we…

Combinatorics · Mathematics 2014-08-26 Qingsong Tang , Yuejian Peng , Xiangde Zhang , Cheng Zhao

We investigate the number of maximal cliques, i.e., cliques that are not contained in any larger clique, in three network models: Erd\H{o}s-R\'enyi random graphs, inhomogeneous random graphs (also called Chung-Lu graphs), and geometric…

Combinatorics · Mathematics 2024-11-27 Thomas Bläsius , Maximillian Katzmann , Clara Stegehuis

A well-known conjecture of Frankl and F\"{u}redi from 1989 states that an initial segment of colex of has the largest Lagrangian of any $r$-uniform hypergraph with $m$ hyperedges. We show that this is true when $r=3$. We also give a new…

Combinatorics · Mathematics 2020-03-20 Vytautas Gruslys , Shoham Letzter , Natasha Morrison

We consider the problem of finding a large clique in an Erd\H{o}s--R\'enyi random graph where we are allowed unbounded computational time but can only query a limited number of edges. Recall that the largest clique in $G \sim G(n,1/2)$ has…

Combinatorics · Mathematics 2024-07-12 Endre Csóka , András Pongrácz

We consider the maximum chromatic number of hypergraphs consisting of cliques that have pairwise small intersections. Designs of the appropriate parameters produce optimal constructions, but these are known to exist only when the number of…

Combinatorics · Mathematics 2023-04-12 Dhruv Mubayi , Jacques Verstraete

An $r$-uniform graph $G$ is dense if and only if every proper subgraph $G'$ of $G$ satisfies $\lambda (G') < \lambda (G)$, where $\lambda (G)$ is the Lagrangian of a hypergraph $G$. In 1980's, Sidorenko showed that $\pi(F)$, the Tur\'an…

Combinatorics · Mathematics 2017-01-24 Biao Wu , Yuejian Peng

In this work, we give the sharp upper bound for the number of cliques in graphs with bounded odd circumferences. This generalized Tur\'an-type result is an extension of the celebrated Erd\H{o}s and Gallai theorem and a strengthening of…

Combinatorics · Mathematics 2022-12-07 Zequn Lv , Ervin Győri , Zhen He , Nika Salia , Chuanqi Xiao , Xiutao Zhu

We study maximal cliques in the collinearity graphs of Desarguesian nets, give some structural results and some numerical information. In particular, we show for Desarguesian nets that the set consisting of a point $x$ together with all its…

Combinatorics · Mathematics 2026-04-28 Andries E. Brouwer , Sergey Goryainov , Leonid Shalaginov , Chi Hoi Yip

Recently Chase determined the maximum possible number of cliques of size $t$ in a graph on $n$ vertices with given maximum degree. Soon afterward, Chakraborti and Chen answered the version of this question in which we ask that the graph…

Combinatorics · Mathematics 2023-08-14 Rachel Kirsch , Jamie Radcliffe

Frankl and F\"uredi conjectured in 1989 that the maximum Lagrangian of all $r$-uniform hypergraphs of fixed size $m$ is realised by the initial segment of the colexicographic order. In particular, in the principal case $m=\binom{t}{r}$…

Combinatorics · Mathematics 2017-10-11 Mykhaylo Tyomkyn
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