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In 2013, Chan classified all metric hyperelliptic graphs, proving that divisorial gonality and geometric gonality are equivalent in the hyperelliptic case. We show that such a classification extends to combinatorial graphs of divisorial…

Combinatorics · Mathematics 2020-03-06 Ivan Aidun , Frances Dean , Ralph Morrison , Teresa Yu , Julie Yuan

A graph $G$ is called \emph{symmetric with respect to a functional $F_G(P)$} defined on the set of all the probability distributions on its vertex set if the distribution $P^*$ maximizing $F_G(P)$ is uniform on $V(G)$. Using the…

Combinatorics · Mathematics 2013-11-27 Seyed Saeed Changiz Rezaei , Chris Godsil

It is well known that a plane graph is Eulerian if and only if its geometric dual is bipartite. We extend this result to partial duals of plane graphs. We then characterize all bipartite partial duals of a plane graph in terms of oriented…

Combinatorics · Mathematics 2013-11-18 Stephen Huggett , Iain Moffatt

Adjacency polytopes, a.k.a. symmetric edge polytopes, associated with undirected graphs have been defined and studied in several seemingly independent areas including number theory, discrete geometry, and dynamical systems. In particular,…

Combinatorics · Mathematics 2020-07-15 Tianran Chen , Evgeniia Korchevskaia

We describe a general construction of strongly regular graphs from the collinearity graph of a finite classical polar spaces of rank at least $3$ over a finite field of order $q$. We show that these graphs are non-isomorphic to the…

Combinatorics · Mathematics 2017-08-01 Ferdinand Ihringer

Let $\Gamma=\Gamma(2n,q)$ be the dual polar graph of type $Sp(2n,q)$. Underlying this graph is a $2n$-dimensional vector space $V$ over a field ${\mathbb F}_q$ of odd order $q$, together with a symplectic (i.e. nondegenerate alternating…

Combinatorics · Mathematics 2015-09-22 G. Eric Moorhouse , Jason Williford

Symmetric edge polytopes, also called adjacency polytopes, are lattice polytopes determined by simple undirected graphs. We introduce the integer array \(\mathrm{maxf}(n,m)\) giving the maximum number of facets of a symmetric edge polytope…

Combinatorics · Mathematics 2023-07-07 Benjamin Braun , Kaitlin Bruegge

We prove that a connected, locally finite, quasi-transitive graph which is quasi-isometric to a planar graph is necessarily accessible. This leads to a complete classification of the finitely generated groups which are quasi-isometric to…

Group Theory · Mathematics 2026-05-14 Joseph Paul MacManus

A level graph is the data of a pair $(G,\pi)$ consisting of a finite graph $G$ and an ordered partition $\pi$ on the set of vertices of $G$. To each level graph on $n$ vertices we associate a polytope in $\mathbb R^n$ called its residue…

Combinatorics · Mathematics 2024-10-18 Omid Amini , Eduardo Esteves , Eduardo Garcez

We prove that every finite arc-transitive graph of valency twice a prime admits a nontrivial semiregular automorphism, that is, a non-identity automorphism whose cycles all have the same length. This is a special case of the Polycirculant…

Combinatorics · Mathematics 2019-01-03 Michael Giudici , Gabriel Verret

In this paper, we give a characterization for a class of edge-transitive Cayley graphs, and provide methods for constructing Cayley graphs with certain symmetry properties. Also this study leads to construct and characterise a new family of…

Group Theory · Mathematics 2016-08-30 Lei Wang

A graph $\G$ admitting a group $H$ of automorphisms acting semi-regularly on the vertices with exactly two orbits is called a {\em bi-Cayley graph\/} over $H$. Such a graph $\G$ is called {\em normal\/} if $H$ is normal in the full…

Combinatorics · Mathematics 2016-06-16 Marston Conder , Jin-Xin Zhou , Yan-Quan Feng , Mi-Mi Zhang

The present work investigates regular, semiregular, and chiral polytopes of any rank $d\geq 3$, whose automorphism groups are 2-groups. There is a large variety of rather small finite regular or alternating semiregular polytopes with…

Group Theory · Mathematics 2025-12-18 Gabriel Cunningham , Yan-Quan Feng , Dong-Dong Hou , Egon Schulte

We show that given a trivalent graph in $S^3$, either the graph complement contains an essential almost meridional planar surface or thin position for the graph is also bridge position. This can be viewed as an extension of a theorem of…

Geometric Topology · Mathematics 2008-07-21 Tao Li

The total matching polytope generalizes the stable set polytope and the matching polytope. In this paper, we first propose new facet-defining inequalities for the total matching polytope. We then give an exponential-sized, non-redundant…

Discrete Mathematics · Computer Science 2023-12-29 Yuri Faenza , Luca Ferrarini

A (3,4)-biregular bigraph G is a bipartite graph where all vertices in one part have degree 3 and all vertices in the other part have degree 4. A path factor of G is a spanning subgraph whose components are nontrivial paths. We prove that a…

Combinatorics · Mathematics 2007-06-13 Armen S. Asratian , Carl Johan Casselgren

For positive integers $s,t,u,v$, we define a bipartite graph $\Gamma_{\mathbb{R}}(X^s Y^t,X^u Y^v)$ where each partite set is a copy of $\mathbb{R}^3$, and a vertex $(a_1,a_2,a_3)$ in the first partite set is adjacent to a vertex…

Combinatorics · Mathematics 2021-01-26 Alex Kodess , Brian G. Kronenthal , Diego Manzano-Ruiz , Ethan Noe

Assume that there is a free group action of automorphisms on a bipartite graph. If there is a perfect matching on the factor graph, then obviously there is a perfect matching on the graph. Surprisingly, the reversed is also true for…

Group Theory · Mathematics 2016-07-26 Jan Fricke

We introduce the concept of pseudocover, which is a counterpart of cover, for symmetric graphs. The only known example of pseudocovers of symmetric graphs so far was given by Praeger, Zhou and the first-named author a decade ago, which…

Combinatorics · Mathematics 2024-12-10 Cai Heng Li , Yan Zhou Zhu

Let $G$ be a finite graph allowing loops, having no multiple edge and no isolated vertex. We associate $G$ with the edge polytope ${\cal P}_G$ and the toric ideal $I_G$. By classifying graphs whose edge polytope is simple, it is proved that…

Commutative Algebra · Mathematics 2018-08-22 Hidefumi Ohsugi , Takayuki Hibi