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An $n$-vertex graph is called pancyclic if it contains a cycle of length $t$ for all $3 \leq t \leq n$. In this paper, we study pancyclicity of random graphs in the context of resilience, and prove that if $p \gg n^{-1/2}$, then the random…

Combinatorics · Mathematics 2015-03-17 Choongbum Lee , Wojciech Samotij

Erd\H{o}s conjectured that every $n$-vertex triangle-free graph contains a subset of $\lfloor n/2\rfloor$ vertices that spans at most $n^2/50$ edges. Extending a recent result of Norin and Yepremyan, we confirm this conjecture for graphs…

Combinatorics · Mathematics 2019-03-05 Wiebke Bedenknecht , Guilherme Oliveira Mota , Christian Reiher , Mathias Schacht

A feedback vertex set of a graph is a subset of vertices intersecting all cycles. We provide tight upper bounds on the size of a minimum feedback vertex set in planar graphs of girth at least five. We prove that if $G$ is a connected planar…

Combinatorics · Mathematics 2016-11-29 Tom Kelly , Chun-Hung Liu

A graph H is a square root of a graph G if G can be obtained from H by adding an edge between any two vertices in H that are of distance 2. The Square Root problem is that of deciding whether a given graph admits a square root. This problem…

Data Structures and Algorithms · Computer Science 2016-08-30 Manfred Cochefert , Jean-François Couturier , Petr A. Golovach , Dieter Kratsch , Daniël Paulusma , Anthony Stewart

In 1973, Erd\H{o}s and Simonovits asked whether every $n$-vertex triangle-free graph with minimum degree greater than $1/3 \cdot n$ is 3-colourable. This question initiated the study of the chromatic profile of triangle-free graphs: for…

Combinatorics · Mathematics 2023-08-22 Freddie Illingworth

The crossing number of a graph is the minimum number of crossings in a drawing of the graph in the plane. Our main result is that every graph $G$ that does not contain a fixed graph as a minor has crossing number $O(\Delta n)$, where $G$…

Combinatorics · Mathematics 2018-08-01 Vida Dujmović , Ken-ichi Kawarabayashi , Bojan Mohar , David R. Wood

Given two graphs $H_1$ and $H_2$, a graph is $(H_1,H_2)$-free if it contains no induced subgraph isomorphic to $H_1$ or $H_2$. Let $P_t$ and $C_t$ be the path and the cycle on $t$ vertices, respectively. A bull is the graph obtained from a…

Combinatorics · Mathematics 2022-11-09 Shenwei Huang , Jiawei Li , Wen Xia

We consider the core algorithmic problems related to verification of systems with respect to three classical quantitative properties, namely, the mean-payoff property, the ratio property, and the minimum initial credit for energy property.…

Data Structures and Algorithms · Computer Science 2015-04-29 Krishnendu Chatterjee , Rasmus Ibsen-Jensen , Andreas Pavlogiannis

Given a locally finite simple graph so that its degree is not bounded, every self-adjoint realization of the adjacency matrix is unbounded from above. In this note we give an optimal condition to ensure it is also unbounded from below. We…

Functional Analysis · Mathematics 2015-05-14 Sylvain Golenia

By definition, a rigid graph in $\mathbb{R}^d$ (or on a sphere) has a finite number of embeddings up to rigid motions for a given set of edge length constraints. These embeddings are related to the real solutions of an algebraic system.…

Combinatorics · Mathematics 2021-10-26 Evangelos Bartzos , Ioannis Z. Emiris , Raimundas Vidunas

Graph and network visualization supports exploration, analysis and communication of relational data arising in many domains: from biological and social networks, to transportation and powergrid systems. With the arrival of AI-based…

Let $s(n)$ be the minimum number of edges in a graph that contains every $n$-vertex tree as a subgraph. Chung and Graham [J. London Math. Soc. 1983] claim to prove that $s(n)\leqslant O(n\log n)$. We point out a mistake in their proof. The…

Combinatorics · Mathematics 2025-08-06 Neel Kaul , David R. Wood

For a graph $G$, a vertex coloring $f$ is called nonrepetitive if for all $k\in\mathbb N$ and all $P_{2k}=\langle v_1, \cdots, v_k,v_{k+1}, \cdots, v_{2k}\rangle$ (path of $2k$ vertices) in $G$, there must be some $1\le i\le k$ such that…

Combinatorics · Mathematics 2024-08-20 Tianyi Tao

Recently, \citeauthor*{akbari2021locality}~(ICALP 2023) studied the locality of graph problems in distributed, sequential, dynamic, and online settings from a {unified} point of view. They designed a novel $O(\log n)$-locality deterministic…

Data Structures and Algorithms · Computer Science 2024-05-02 Yi-Jun Chang , Gopinath Mishra , Hung Thuan Nguyen , Mingyang Yang , Yu-Cheng Yeh

Let $P_n$ and $K_n$ denote the induced path and complete graph on $n$ vertices, respectively. The {\em kite} is the graph obtained from a $P_4$ by adding a vertex and making it adjacent to all vertices in the $P_4$ except one vertex with…

Combinatorics · Mathematics 2022-04-20 Shenwei Huang , Yiao Ju , T. Karthick

The smallest set of vertices needed to differentiate or categorize every other vertex in a graph is referred to as the graph's metric dimension. Finding the class of graphs for a particular given metric dimension is an NP-hard problem. This…

Combinatorics · Mathematics 2023-11-07 Amal S. Alali , Shahbaz Ali , Muhammad Adnan , Delfim F. M. Torres

We study the minimum degree necessary to guarantee the existence of perfect and almost-perfect triangle-tilings in an $n$-vertex graph $G$ with sublinear independence number. In this setting, we show that if $\delta(G) \ge n/3 + o(n)$ then…

Combinatorics · Mathematics 2016-07-27 József Balogh , Andrew McDowell , Theodore Molla , Richard Mycroft

In the study of deterministic distributed algorithms it is commonly assumed that each node has a unique $O(\log n)$-bit identifier. We prove that for a general class of graph problems, local algorithms (constant-time distributed algorithms)…

Distributed, Parallel, and Cluster Computing · Computer Science 2013-12-24 Mika Göös , Juho Hirvonen , Jukka Suomela

Since its formulation, Tur\'an's hypergraph problems have been among the most challenging open problems in extremal combinatorics. One of them is the following: given a $3$-uniform hypergraph $\mathcal{F}$ on $n$ vertices in which any five…

Combinatorics · Mathematics 2020-04-24 Peter Frankl , Hao Huang , Vojtěch Rödl

We consider the problem of finding a cycle in a sparse directed graph $G$ that is promised to be far from acyclic, meaning that the smallest feedback arc set in $G$ is large. We prove an information-theoretic lower bound, showing that for…

Data Structures and Algorithms · Computer Science 2019-07-30 Xi Chen , Tim Randolph , Rocco A. Servedio , Timothy Sun