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Community search aims at finding densely connected subgraphs for query vertices in a graph. While this task has been studied widely in the literature, most of the existing works only focus on finding homogeneous communities rather than…

Social and Information Networks · Computer Science 2021-05-21 Zheng Dong , Xin Huang , Guorui Yuan , Hengshu Zhu , Hui Xiong

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 $i$-independent set is a vertex set whose pairwise distance is at least $i+1$. A proper (square) $k$-coloring of a graph $G$ is a partition of its vertex set into $k$ independent ($2$-independent) sets. A packing $(1^{j}, 2^k)$-coloring…

Combinatorics · Mathematics 2026-04-02 Xujun Liu , Zihui Xu , Xin Zhang

A family of sets is said to be intersecting if every pair of sets in the family have non-empty intersection. In this paper, we initiate the study of intersecting non-uniform families of sets of one of two sizes containing given subfamilies.…

Combinatorics · Mathematics 2019-02-19 Carl Feghali

There has been interest recently in maximizing the number of independent sets in graphs. For example, the Kahn-Zhao theorem gives an upper bound on the number of independent sets in a $d$-regular graph. Similarly, it is a corollary of the…

Combinatorics · Mathematics 2019-03-21 Lauren Keough , A. J. Radcliffe

We prove that any family $E_1, \ldots , E_{\lceil rn \rceil}$ of (not necessarily distinct) sets of edges in an $r$-uniform hypergraph, each having a fractional matching of size $n$, has a rainbow fractional matching of size $n$ (that is, a…

Combinatorics · Mathematics 2020-01-27 Ron Aharoni , Ron Holzman , Zilin Jiang

We propose a scalable approximate algorithm for the NP-hard maximum-weight independent set problem. The core component of our algorithm is a dual coordinate descent applied to a smoothed LP relaxation of the problem. This technique is…

Optimization and Control · Mathematics 2025-03-27 Stefan Haller , Bogdan Savchynskyy

An independent set A is maximal if it is not a proper subset of an independent set, while A is maximum if it has a maximum size. The problem of whether a graph has a pair of disjoint maximal independent sets was introduced by C. Berge in…

Combinatorics · Mathematics 2019-02-01 Zakir Deniz , Vadim E. Levit , Eugen Mandrescu

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

Given a hypergraph H = (V, E), a coloring of its vertices is said to be conflict-free if for every hyperedge S \in E there is at least one vertex in S whose color is distinct from the colors of all other vertices in S. The discrete interval…

Combinatorics · Mathematics 2012-05-01 Panagiotis Cheilaris , Shakhar Smorodinsky

A \emph{co-bipartite chain} graph is a co-bipartite graph in which the neighborhoods of the vertices in each clique can be linearly ordered with respect to inclusion. It is known that the maximum cut problem (MaxCut) is NP-Hard in…

Data Structures and Algorithms · Computer Science 2015-04-15 Arman Boyacı , Tınaz Ekim , Mordechai Shalom

We present approximation algorithms for maximum independent set of pseudo-disks in the plane, both in the weighted and unweighted cases. For the unweighted case, we prove that a local search algorithm yields a \PTAS. For the weighted case,…

Computational Geometry · Computer Science 2011-03-09 Timothy M. Chan , Sariel Har-Peled

We relate two complexity notions of bipartite graphs: the minimal weight biclique covering number $\mathrm{Cov}(G)$ and the minimal rectifier network size $\mathrm{Rect}(G)$ of a bipartite graph $G$. We show that there exist graphs with…

Formal Languages and Automata Theory · Computer Science 2014-06-03 Szabolcs Iván , Ádám Dániel Lelkes , Judit Nagy-György , Balázs Szörényi , György Turán

Given a set ${\cal R}=\{R_1,R_2,..., R_n\}$ of $n$ randomly positioned axis parallel rectangles in 2D, the problem of computing the minimum clique cover (MCC) and maximum independent set (MIS) for the intersection graph $G({\cal R})$ of the…

Computational Geometry · Computer Science 2012-12-05 Ritankar Mandal , Anirban Ghosh , Sasanka Roy , Subhas C. Nandy

We study the algorithmic task of finding a large independent set in a sparse Erd\H{o}s-R\'{e}nyi random graph with $n$ vertices and average degree $d$. The maximum independent set is known to have size $(2 \log d / d)n$ in the double limit…

Computational Complexity · Computer Science 2020-11-13 Alexander S. Wein

Roughly speaking, an $(n,(r,s))$-Cover Free Family (CFF) is a small set of $n$-bit strings such that: "in any $d:=r+s$ indices we see all patterns of weight $r$". CFFs have been of interest for a long time both in discrete mathematics as…

Discrete Mathematics · Computer Science 2015-07-28 Nader H. Bshouty , Ariel Gabizon

Best match graphs (BMGs) are vertex-colored digraphs that naturally arise in mathematical phylogenetics to formalize the notion of evolutionary closest genes w.r.t. an a priori unknown phylogenetic tree. BMGs are explained by unique least…

Data Structures and Algorithms · Computer Science 2021-03-12 David Schaller , Manuela Geiß , Marc Hellmuth , Peter F. Stadler

For any $\varepsilon > 0$, we give a polynomial-time $n^\varepsilon$-approximation algorithm for Max Independent Set in graphs of bounded twin-width given with an $O(1)$-sequence. This result is derived from the following time-approximation…

Data Structures and Algorithms · Computer Science 2022-09-27 Pierre Bergé , Édouard Bonnet , Hugues Déprés , Rémi Watrigant

Bicyclic graph is a connected graph in which the number of edges equals the number of vertices plus one. In this paper, we determine the graph which alone maximizes the spectral radii among all the bicyclic graphs on $n$ vertices with fixed…

Combinatorics · Mathematics 2014-02-25 Xiying Yuan

Given a bipartite graph, the maximum balanced biclique (\textsf{MBB}) problem, discovering a mutually connected while equal-sized disjoint sets with the maximum cardinality, plays a significant role for mining the bipartite graph and has…

Data Structures and Algorithms · Computer Science 2020-07-20 Lu Chen , Chengfei Liu , Rui Zhou , Jiajie Xu , Jianxin Li