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If the face\mbox{-}cycles at all the vertices in a map are of the same type, then the map is said to be a semi-equivelar map. Automorphism (symmetry) of a map can be thought of as a permutation of the vertices which preserves the…

Combinatorics · Mathematics 2021-01-13 Marbarisha M. Kharkongor , Debashis Bhowmik , Dipendu Maity

We introduce binomial edge ideals attached to a simple graph $G$ and study their algebraic properties. We characterize those graphs for which the quadratic generators form a Gr\"obner basis in a lexicographic order induced by a vertex…

Commutative Algebra · Mathematics 2009-10-16 Juergen Herzog , Takayuki Hibi , Freyja Hreinsdottir , Thomas Kahle , Johannes Rauh

We classify all unicycle graphs whose edge-binomials form a $d$-sequence, particularly linear type binomial edge ideals. We also classify unicycle graphs whose parity edge-binomials form a $d$-sequence. We study the regularity of powers of…

Commutative Algebra · Mathematics 2024-03-19 Marie Amalore Nambi , Neeraj Kumar

A biased graph consists of a graph $G$ together with a collection of distinguished cycles of $G$, called balanced cycles, with the property that no theta subgraph contains exactly two balanced cycles. Perhaps the most natural biased graphs…

Combinatorics · Mathematics 2014-07-28 Matt DeVos , Daryl Funk , Irene Pivotto

Building on earlier results for regular maps and for orientably regular chiral maps, we classify the non-abelian finite simple groups arising as automorphism groups of maps in each of the 14 Graver-Watkins classes of edge-transitive maps.

Group Theory · Mathematics 2021-07-13 Gareth A. Jones

Rotary maps (orientably regular maps) are highly symmetric graph embeddings on orientable surfaces. This paper classifies all rotary maps whose underlying graphs are Praeger-Xu graphs, denoted $\operatorname{C}(p,r,s)$, for any odd prime…

Combinatorics · Mathematics 2025-07-03 Zhaochen Ding , Zheng Guo , Luyi Liu

We classify all graphs for which the Rees algebras of their edge ideals are normal and have regularity equal to their matching numbers.

Commutative Algebra · Mathematics 2024-05-21 Cao Huy Linh , Quang Hoa Tran , Thanh Vu

A bipartite graph $G=(V,E)$ with $V=V_1\cup V_2$ is biregular if all the vertices of each stable set, $V_1$ and $V_2$, have the same degree, $r$ and $s$, respectively. This paper studies difference sets derived from both Abelian and…

Combinatorics · Mathematics 2024-04-09 G. Araujo-Pardo , C. Dalfó , M. A. Fiol , N. López

Structurally stable (rough) flows on surfaces have only finitely many singularities and finitely many closed orbits, all of which are hyperbolic, and they have no trajectories joining saddle points. The violation of the last property leads…

Dynamical Systems · Mathematics 2017-06-07 Vladislav Kruglov , Dmitry Malyshev , Olga Pochinka

In this paper, we define irregular bipolar fuzzy graphs and its various classifications. Size of regular bipolar fuzzy graphs is derived. The relation between highly and neighbourly irregular bipolar fuzzy graphs are established. Some basic…

Discrete Mathematics · Computer Science 2012-09-11 Sovan Samanta , Madhumangal Pal

Let $G$ be a finite simple graph and $I(G)$ denote the corresponding edge ideal. For all $s \geq 1$, we obtain upper bounds for reg$(I(G)^s)$ for bipartite graphs. We then compare the properties of $G$ and $G'$, where $G'$ is the graph…

Commutative Algebra · Mathematics 2016-09-07 A V Jayanthan , N Narayanan , S Selvaraja

We enumerate and classify all the semi equivelar maps on the surface of $ \chi=-2 $ with up to 12 vertices. We also determine which of these are vertex-transitive and which are not.

Geometric Topology · Mathematics 2019-04-17 Debashis Bhowmik , Ashish Kumar Upadhyay

We characterise the quintic (i.e. 5-regular) multigraphs with the property that every edge lies in a triangle. Such a graph is either from a set of small graphs or is formed by adding a perfect matching to a line graph of a cubic graph as…

Combinatorics · Mathematics 2021-07-09 James Preen

The groups which can act semisymmetrically on a cubic graph of twice odd order are determined modulo a normal subgroup which acts semiregularly on the vertices of the graph.

Group Theory · Mathematics 2007-05-23 Chris Parker

There is a natural infinite graph whose vertices are the monomial ideals in a polynomial ring. The definition involves Gr\"obner bases or the action of an algebraic torus. We present algorithms for computing the (affine schemes…

Commutative Algebra · Mathematics 2007-05-23 Klaus Altmann , Bernd Sturmfels

We classify all graphs $G$ satisfying the property that all matching powers $I(G)^{[k]}$ of the edge ideal $I(G)$ are bi-Cohen-Macaulay for $1\le k\le\nu(G)$, where $\nu(G)$ is the maximum size of a matching of $G$.

Commutative Algebra · Mathematics 2025-08-05 Marilena Crupi , Antonino Ficarra

In this note we prove an effective characterization of when two finite-degree covers of a connected, orientable surface of negative Euler characteristic are isomorphic in terms of which curves have simple elevations, weakening the…

Geometric Topology · Mathematics 2023-07-20 Tarik Aougab , Max Lahn , Marissa Loving , Nicholas Miller

We provide weak-type bounds for a family of bilinear fractional integrals that arise in the study of Euler-Riesz systems. These bounds are uniform in the natural parameter that describes the family and are sharp, in the sense that they do…

Classical Analysis and ODEs · Mathematics 2025-08-12 Nuno J. Alves , Loukas Grafakos

Let $J_G$ be the binomial edge ideal of a graph $G$. We characterize all graphs whose binomial edge ideals, as well as their initial ideals, have regularity $3$. Consequently we characterize all graphs $G$ such that $J_G$ is extremal…

Commutative Algebra · Mathematics 2017-06-29 Sara Saeedi Madani , Dariush Kiani

We provide a characterisation of all graphs whose parity binomial edge ideals have pure resolutions. In particular, we show that the minimal free resolution of a parity binomial edge ideal is pure if and only if the corresponding graph is a…

Commutative Algebra · Mathematics 2020-11-17 Peter Phelan