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Related papers: A Lower Bound on the Diameter of the Flip Graph

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In this paper, we investigate how the Wiener index of unicyclic graphs varies with graph operations. These results are used to present a sharp lower bound for the Wiener index of unicyclic graphs of order $n$ with girth and the matching…

Combinatorics · Mathematics 2011-03-01 Ya-Hong Chen , Xiao-Dong Zhang

In this paper, we study the connectedness of the commuting graph of a general Lie algebra and provide a process to determine whether the commuting graph is connected or not, as well as to compute an upper bound for its diameter. In…

Rings and Algebras · Mathematics 2024-05-13 Hieu V. Ha , Hoa D. Quang , Vu A. Le , Tuyen T. M Nguyen

For any finite set $\A$ of $n$ points in $\R^2$, we define a $(3n-3)$-dimensional simple polyhedron whose face poset is isomorphic to the poset of ``non-crossing marked graphs'' with vertex set $\A$, where a marked graph is defined as a…

Combinatorics · Mathematics 2007-05-23 David Orden , Francisco Santos

Let $k_r(n,\delta)$ be the minimum number of $r$-cliques in graphs with $n$ vertices and minimum degree $\delta$. We evaluate $k_r(n,\delta)$ for $\delta \leq 4n/5$ and some other cases. Moreover, we give a construction, which we conjecture…

Combinatorics · Mathematics 2010-09-28 Allan Lo

In 2002, Koh and Tay conjectured that every bridgeless graph of order $n\geq 5$ and size at least ${n\choose 2}-n+5$ has an orientation of diameter two. Later, Cochran, Czabarka, Dankelmann and Sz\'{e}kely proved this conjecture and asked…

Combinatorics · Mathematics 2025-08-26 Sopon Boriboon , Teeradej Kittipassorn

In this paper, we introduce a flip operation on self-complementary ideals of chain product posets and study the resulting flip graphs. We give asymptotics for the number of vertices in these graphs, compute their diameters, and give bounds…

Combinatorics · Mathematics 2024-01-05 Serena An , Holden Mui

For $S\subseteq V(G)$ and $|S|\geq 2$, $\lambda(S)$ is the maximum number of edge-disjoint trees connecting $S$ in $G$. For an integer $k$ with $2\leq k\leq n$, the \emph{generalized $k$-edge-connectivity} $\lambda_k(G)$ of $G$ is then…

Combinatorics · Mathematics 2013-07-10 Xueliang Li , Yaping Mao

For the right-angled Artin group action on the extension graph, it is known that the minimal asymptotic translation length is bounded above by 2 provided that the defining graph has diameter at least 3. In this paper, we show that the same…

Geometric Topology · Mathematics 2024-10-22 Eon-Kyung Lee , Sang-Jin Lee

A Delaunay graph built on a planar point set has an edge between two vertices when there exists a disk with the two vertices on its boundary and no vertices in its interior. When the disk is replaced with an equilateral triangle, the…

Computational Geometry · Computer Science 2025-06-17 Prosenjit Bose , Jean-Lou De Carufel , John Stuart

In this paper, we study the flip graph on the perfect matchings of a complete graph of even order. We investigate its combinatorial and spectral properties including connections to the signed reversal graph and we improve a previous upper…

Combinatorics · Mathematics 2021-10-20 Sebastian M. Cioabă , Gordon Royle , Zhao Kuang Tan

A graph is $1$-$planar$ if it can be drawn in the plane so that each edge is crossed by at most one other edge. Moreover, a 1-planar graph $G$ is $optimal$ if it satisfies $|E(G)|=4|V(G)|-8$. J. Fujisawa et al. [16] first considered…

Combinatorics · Mathematics 2022-05-25 Jiangyue Zhang , Yan Wu , Heping Zhang

The edge-bandwidth of a graph is the minimum, over all labelings of the edges with distinct integers, of the maximum difference between labels of two incident edges. We prove that edge-bandwidth is at least as large as bandwidth for every…

Combinatorics · Mathematics 2007-05-23 Tao Jiang , Dhruv Mubayi , Aditya Shastri , Douglas B. West

In a region $R$ consisting of unit squares, a domino is the union of two adjacent squares and a (domino) tiling is a collection of dominoes with disjoint interior whose union is the region. The flip graph $\mathcal{T}(R)$ is defined on the…

Combinatorics · Mathematics 2022-11-22 Qianqian Liu , Jingfeng Wang , Chunmei Li , Heping Zhang

A graph is chordal if it does not contain an induced cycle of length greater than three. We determine the minimum size of a chordal graph with given order and minimum degree. In doing so, we have discovered interesting properties of chordal…

Combinatorics · Mathematics 2024-09-17 Xingzhi Zhan , Leilei Zhang

There is a graph reduction system so that every optimal 1-planar graph can be reduced to an irreducible extended wheel graph, provided the reductions are applied such that the given graph class is preserved. A graph is optimal 1-planar if…

Computational Geometry · Computer Science 2016-10-28 Franz J. Brandenburg

We consider the following long range percolation model: an undirected graph with the node set $\{0,1,...,N\}^d$, has edges $(\x,\y)$ selected with probability $\approx \beta/||\x-\y||^s$ if $||\x-\y||>1$, and with probability 1 if…

Probability · Mathematics 2007-05-23 Don Coppersmith , David Gamarnik , Maxim Sviridenko

A mixed graph $G$ can contain both (undirected) edges and arcs (directed edges). Here we derive an improved Moore-like bound for the maximum number of vertices of a mixed graph with diameter at least three. Moreover, a complete enumeration…

Combinatorics · Mathematics 2018-04-26 C. Dalfó , M. A. Fiol , N. López

For an angle $\alpha\in (0,\pi)$, we consider plane graphs and multigraphs in which the edges are either (i) one-bend polylines with an angle $\alpha$ between the two edge segments, or (ii) circular arcs of central angle $2(\pi-\alpha)$. We…

Discrete Mathematics · Computer Science 2023-11-28 Csaba D. Tóth

Given a connected graph $G$ on $n$ vertices, with minimum degree $\delta\geq 2$ and girth at least $g \geq 4$, what is the maximum radius $r$ this graph can have? Erd\H{o}s, Pach, Pollack and Tuza established in the triangle-free case…

Combinatorics · Mathematics 2020-09-07 Vojtěch Dvořák , Peter van Hintum , Amy Shaw , Marius Tiba

A graph $G$ is said to be $F$-free if it does not contain $F$ as a subgraph. A theta graph, say $\theta_{l_1,l_2,l_3}$, is the graph obtained by connecting two distinct vertices with three internally disjoint paths of length $l_1, l_2,…

Combinatorics · Mathematics 2024-10-11 Jing Gao , Xueliang Li