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In this note we construct two infinite snark families which have high oddness and low circumference compared to the number of vertices. Using this construction, we also give a counterexample to a suggested strengthening of Fulkerson's…

Combinatorics · Mathematics 2012-03-12 Jonas Hägglund

In this paper, we give the classification of circulant graphs $C(\mathbb{Z}_{n},S)$ with $|S|=2$ and completely solve the dispersability of circulant graphs $C(\mathbb{Z}_{n},\{1, k\})$.

Combinatorics · Mathematics 2023-10-11 Xiaoxiang Yu , Zeling Shao , Zhiguo Li

Building on techniques from complex analysis and topology, we establish a remarkable property of branched covers and formulate a complete criterion for the existence of specific types of branched covers between 2-spheres. Our results extend…

Geometric Topology · Mathematics 2025-04-10 Yingjie Meng , Zhiqiang Wei , Chuankai Zhou

Let $R=K[x_1,\ldots,x_n]$ be the polynomial ring in $n$ variables over a field $K$. We show that if $G$ is a connected graph with a basic $5$-cycle $C$, then $G$ is a sequentially Cohen-Macaulay graph if and only if there exists a shedding…

Commutative Algebra · Mathematics 2024-05-24 Mozhgan Koolani , Amir Mafi

Two graphs having the same spectrum are said to be cospectral. Two graphs such that the absolute values of their nonzero eigenvalues coincide are singularly cospectral graphs. Cospectrality implies singular cospectrality, but the converse…

Combinatorics · Mathematics 2024-08-15 Cristian M. Conde , Ezequiel Dratman , Luciano N. Grippo , Melina Privitelli

A number of authors have studied the question of when a graph can be represented as a Cayley graph on more than one nonisomorphic group. The work to date has focussed on a few special situations: when the groups are $p$-groups; when the…

Combinatorics · Mathematics 2020-05-26 Joy Morris , Josip Smolcic

In this paper, we characterise the family of finite arc-transitive bicirculants. We show that every finite arc-transitive bicirculant is a normal $r$-cover of an arc-transitive graph that lies in one of eight infinite families or is one of…

Combinatorics · Mathematics 2022-01-25 Alice Devillers , Michael Giudici , Wei Jin

We extend the definition of chordal from graphs to clutters. The resulting family generalizes both chordal graphs and matroids, and obeys many of the same algebraic and geometric properties. Specifically, the independence complex of a…

Combinatorics · Mathematics 2021-08-24 Russ Woodroofe

We graph-theoretically characterize triangle-free Gorenstein graphs $G$. As an application, we classify when $I(G)^2$ is Cohen-Macaulay.

Commutative Algebra · Mathematics 2015-09-01 Do Trong Hoang , Tran Nam Trung

This note is a continuation of the study of the relationship between the geometry of Cayley graphs and the size of its metric-functional boundary. We show that, if there exists a Cayley graph with finitely many Busemann points, then the…

Group Theory · Mathematics 2025-11-27 Corentin Bodart , Liran Ron-George , Ariel Yadin

For a graph $G$, Bolognini et al. have shown $J_{G}$ is strongly unmixed $\Rightarrow$ $J_{G}$ is Cohen-Macaulay $\Rightarrow$ $G$ is accessible, where $J_{G}$ denotes the binomial edge ideals of $G$. Accessible and strongly unmixed…

Commutative Algebra · Mathematics 2022-03-10 Kamalesh Saha , Indranath Sengupta

Let G be a simple undirected graph on n vertices, and let I(G) \subseteq R = k[x_1,...,x_n] denote its associated edge ideal. We show that all chordal graphs G are sequentially Cohen-Macaulay; our proof depends upon showing that the…

Commutative Algebra · Mathematics 2007-06-13 Christopher A. Francisco , Adam Van Tuyl

Some recent investigations indicate that for the classification of Cohen-Macaulay binomial edge ideals, it suffices to consider biconnected graphs with some whiskers attached (in short, `block with whiskers'). This paper provides explicit…

Commutative Algebra · Mathematics 2024-09-04 Om Prakash Bhardwaj , Kamalesh Saha

We first construct the total simplicial complex (TSC) of a finite simple graph $G$ in order to generalize the total graph $T(G)$. We show that $\Delta_T(G)$ is not Cohen-Macaulay (CM) in general. For a connected graph $G$, we prove that the…

Combinatorics · Mathematics 2023-10-17 Najam Ul Abbas , Imran Ahmed , Ayesha Kiran

Recently, Daligault, Rao and Thomass\'e asked in [3] if every hereditary class which is well-quasi-ordered by the induced subgraph relation is of bounded clique-width. There are two reasons why this questions is interesting. First, it…

Combinatorics · Mathematics 2015-08-26 Aistis Atminas , Vadim V. Lozin , Igor Razgon

It is conjectured by Berge and Fulkerson that every bridgeless cubic graph has six perfect matchings such that each edge is contained in exactly two of them. H$\ddot{a}$gglund constructed two graphs Blowup$(K_4, C)$ and Blowup$(Prism,…

Combinatorics · Mathematics 2017-08-25 Ting Zheng , Rong-Xia Hao

The Kohayakawa-Nagle-R\"odl-Schacht conjecture roughly states that every sufficiently large locally $d$-dense graph $G$ on $n$ vertices must contain at least $(1-o(1))d^{|E(H)|}n^{|V(H)|}$ copies of a fixed graph $H$. Despite its important…

Combinatorics · Mathematics 2019-08-12 Joonkyung Lee

A Graph is called 2-self-centered if its diameter and radius both equal to 2. In this paper, we begin characterizing these graphs by characterizing edge-maximal 2-self-centered graphs via their complements. Then we split characterizing…

Combinatorics · Mathematics 2019-10-29 Mohammad Hadi Shekarriz , Madjid Mirzavaziri , Kamyar Mirzavaziri

This paper studies the Manickam-Mikl\'os-Singhi (MMS) property for graphs and hypergraphs. Using the structural characterisation of the $2$-uniform case, we construct new families of regular graphs with the MMS property. We then analyse the…

Combinatorics · Mathematics 2026-05-22 Adam Džavoronok

Benjamini and Schramm introduced the notion of distributional limit of a sequence of graphs with uniformly bounded valence and studied such limits in the case that the involved graphs are planar. We investigate distributional limits of…

Metric Geometry · Mathematics 2013-09-05 Hossein Namazi , Pekka Pankka , Juan Souto
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