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Unitary graphs are arc-transitive graphs with vertices the flags of Hermitian unitals and edges defined by certain elements of the underlying finite fields. They played a significant role in a recent classification of a class of…

Combinatorics · Mathematics 2015-03-25 Sanming Zhou

We unify several seemingly different graph and digraph classes under one umbrella. These classes are all broadly speaking different generalizations of interval graphs, and include, in addition to interval graphs, also adjusted interval…

Discrete Mathematics · Computer Science 2018-06-28 Pavol Hell , Jing Huang , Ross M. McConnell , Arash Rafiey

Gallai asked in 1984 if any $k$-critical graph on $n$ vertices contains at least $n$ distinct $(k-1)$-critical subgraphs. The answer is trivial for $k\leq 3$. Improving a result of Stiebitz, Abbott and Zhou proved in 1995 that for all…

Combinatorics · Mathematics 2019-07-02 Jie Ma , Tianchi Yang

The expressive power of graph neural network formalisms is commonly measured by their ability to distinguish graphs. For many formalisms, the k-dimensional Weisfeiler-Leman (k-WL) graph isomorphism test is used as a yardstick. In this paper…

Machine Learning · Computer Science 2020-07-24 Floris Geerts

For integers $k \geq 2$ and $n \geq k+1$, we prove the following: If $n\cdot k$ is even, there is a connected $k$-regular graph on $n$ vertices. If $n\cdot k$ is odd, there is a connected nearly $k$-regular graph on $n$ vertices.

Combinatorics · Mathematics 2018-01-26 Ghurumuruhan Ganesan

There has been extensive research on cycle lengths in graphs with large minimum degree. In this paper, we obtain several new and tight results in this area. Let $G$ be a graph with minimum degree at least $k+1$. We prove that if $G$ is…

Combinatorics · Mathematics 2015-09-01 Chun-Hung Liu , Jie Ma

We prove that any \(2\)-connected graph \(G\) on \(n\) vertices with minimum degree \(\delta(G) \ge \frac{n}{4}+2\) contains a \(2\)-connected subgraph of order \(k\) for every integer \(k\) with \(4 \le k \le n\). This improves a previous…

Combinatorics · Mathematics 2026-03-13 Haiyang Liu , Bo Ning

A queue layout of a graph consists of a linear order on the vertices and an assignment of the edges to queues, such that no two edges in a single queue are nested. The minimum number of queues needed in a queue layout of a graph is called…

Discrete Mathematics · Computer Science 2016-08-23 Veit Wiechert

Given a graph $G=(V,E)$ on $n$ vertices and an integer $k$ between 1 and $n-1$, the $k$-token graph $F_k(G)$ has vertices representing the $k$-subsets of $V$, and two vertices are adjacent if their symmetric difference is the two…

Combinatorics · Mathematics 2024-12-31 X. Song , C. Dalfó , M. A. Fiol , S. Zhang

A graph $G$ is a prime distance graph (respectively, a 2-odd graph) if its vertices can be labeled with distinct integers such that for any two adjacent vertices, the difference of their labels is prime (either 2 or odd). We prove that…

Combinatorics · Mathematics 2021-06-07 Joshua D. Laison , Colin Starr , Andrea Walker

A poset $P= (X, \prec)$ has an interval representation if each $x \in X$ can be assigned a real interval $I_x$ so that $x \prec y$ in $P$ if and only if $I_x$ lies completely to the left of $I_y$. Such orders are called \emph{interval…

Combinatorics · Mathematics 2018-04-11 Simona Boyadzhiyska , Garth Isaak , Ann Trenk

An edge-coloring of a graph $G$ with colors $1,2,\ldots,t$ is an interval $t$-coloring if all colors are used, and the colors of edges incident to each vertex of $G$ are distinct and form an interval of integers. A graph $G$ is interval…

Discrete Mathematics · Computer Science 2016-04-01 Hrant H. Khachatrian , Petros A. Petrosyan

We consider a greedy version of the $m$-Tamari order defined on $m$-Dyck paths, recently introduced by Dermenjian. Inspired by intriguing connections between intervals in the ordinary 1-Tamari order and planar triangulations, and more…

Combinatorics · Mathematics 2025-04-11 Mireille Bousquet-Mélou , Frédéric Chapoton

Let $\Gamma$ be a graph equipped with a Markov operator $P$. We introduce discrete fractional Littlewood-Paley square functionals and prove their $L^p$-boundedness under various geometric assumptions on $\Gamma$.

Functional Analysis · Mathematics 2015-06-10 Joseph Feneuil

For any natural number $d$, a graph $G$ is a (disjoint) $d$-interval graph if it is the intersection graph of (disjoint) $d$-intervals, the union of $d$ (disjoint) intervals on the real line. Two important subclasses of $d$-interval graphs…

Discrete Mathematics · Computer Science 2024-04-30 Virginia Ardévol Martínez , Romeo Rizzi , Abdallah Saffidine , Florian Sikora , Stéphane Vialette

In 1991, Gnanajothi [4] proved that the path graph P_n with n vertex and n-1 edge is odd graceful, and the cycle graph C_m with m vertex and m edges is odd graceful if and only if m even, she proved the cycle graph is not graceful if m odd.…

Information Theory · Computer Science 2010-04-22 M. Ibrahim Moussa

In 1991, Gnanajothi [4] proved that the path graph P_n with n vertex and n-1 edge is odd graceful, and the cycle graph C_m with m vertex and m edges is odd graceful if and only if m even, she proved the cycle graph is not graceful if m odd.…

Networking and Internet Architecture · Computer Science 2010-07-15 M. Ibrahim Moussa

We show the nonequivalence of combinations of several natural geometric restrictions on trapezoid representations of trapezoid orders. Each of the properties unit parallelogram, unit trapezoid and proper parallelogram, unit trapezoid and…

Combinatorics · Mathematics 2016-09-07 Stephen Ryan

The generalized $k$-connectivity $\kappa_k(G)$ of a graph $G$ was introduced by Chartrand et al. in 1984, which is a nice generalization of the classical connectivity. Recently, as a natural counterpart, Li et al. proposed the concept of…

Combinatorics · Mathematics 2013-04-24 Lily Chen , Xueliang Li , Mengmeng Liu , Yaping Mao

The type-I intermittency route to (or out of) chaos is investigated within the Horizontal Visibility graph theory. For that purpose, we address the trajectories generated by unimodal maps close to an inverse tangent bifurcation and…

Chaotic Dynamics · Physics 2015-06-12 Ángel M. Núñez , Bartolo Luque , Lucas Lacasa , José Patricio Gómez , Alberto Robledo
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