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It was conjectured by Mkrtchyan, Petrosyan, and Vardanyan that every graph $G$ with $\Delta(G)-\delta(G) \le 1$ has a maximum matching $M$ such that any two $M$-unsaturated vertices do not share a neighbor. In this note, we confirm the…

Combinatorics · Mathematics 2016-11-22 Dong Ye

We show that the $f$-vector of Galashin's poset associahedron $\mathscr A(P)$ only depends on the comparability graph of $P$. In particular, this allows us to produce a family of polytopes with the same $f$-vectors as permutohedra, but that…

Combinatorics · Mathematics 2023-10-03 Son Nguyen , Andrew Sack

This paper is devoted to the construction of norm-preserving maps between bounded cohomology groups. For a graph of groups with amenable edge groups we construct an isometric embedding of the direct sum of the bounded cohomology of the…

For $g\ge 2$ and $n\ge 0$, let $\mathcal{H}_{g,n}\subset \mathcal{M}_{g,n}$ denote the complex moduli stack of $n$-marked smooth hyperelliptic curves of genus $g$. A normal crossings compactification of this space is provided by the theory…

Algebraic Geometry · Mathematics 2024-11-07 Madeline Brandt , Melody Chan , Siddarth Kannan

The GIT chamber decomposition arising from a subtorus action on a quasiprojective toric variety is a polyhedral complex. Denote by Sigma the fan that is the cone over the polyhedral complex. In this paper we show that the toric variety…

Algebraic Geometry · Mathematics 2007-05-23 Alastair Craw , Diane Maclagan

We initiate the algorithmic study of the following "structured augmentation" question: is it possible to increase the connectivity of a given graph G by superposing it with another given graph H? More precisely, graph F is the superposition…

Data Structures and Algorithms · Computer Science 2017-06-15 Fedor V. Fomin , Petr A. Golovach , Dimitrios M. Thilikos

Real-world graphs have inherently complex and diverse topological patterns, known as topological heterogeneity. Most existing works learn graph representation in a single constant curvature space that is insufficient to match the complex…

Machine Learning · Computer Science 2024-12-17 Zihao Guo , Qingyun Sun , Haonan Yuan , Xingcheng Fu , Min Zhou , Yisen Gao , Jianxin Li

\Graph similarity computation is an essential task in many real-world graph-related applications such as retrieving the similar drugs given a query chemical compound or finding the user's potential friends from the social network database.…

Machine Learning · Computer Science 2024-12-18 Jingjing Wang , Hongjie Zhu , Haoran Xie , Fu Lee Wang , Xiaoliang Xu , Yuxiang Wang

A connected graph $G$, of order two or more, is matching covered if each edge lies in some \pema. The tight cut decomposition of a matching covered graph $G$ yields a list of bricks and braces; as per a theorem of Lov{\'a}sz~\cite{lova87},…

Combinatorics · Mathematics 2019-12-18 Fuliang Lu , Nishad Kothari , Xing Feng , Lianzhu Zhang

In 2011, the second author conjectured that every line graph $G$ satisfies $\chi(G)\le \max\{\omega(G),\frac{5\Delta(G)+8}{6}\}$. This conjecture is best possible, as shown by replacing each edge in a 5-cycle by $k$ parallel edges, and…

Combinatorics · Mathematics 2018-06-19 Daniel W. Cranston , Landon Rabern

Following DeMeyer, Ford & Miranda [DFM93], we define a topology on a fan by declaring open sets to be its subfans. Then, like Kato [Kat94], we make our fans into monoided spaces by associating a sheaf of monoids to each fan. (Our sheaf of…

Algebraic Geometry · Mathematics 2007-05-23 Howard M Thompson

Let $G$ be a finite simple graph. The line graph $L(G)$ represents the adjacencies between edges of $G$. We define first the line simplicial complex $\Delta_L(G)$ of $G$ containing Gallai and anti-Gallai simplicial complexes…

Algebraic Topology · Mathematics 2017-08-04 Imran Ahmed , Shahid Muhmood

For a simple drawing $D$ of the complete graph $K_n$, two (plane) subdrawings are compatible if their union is plane. Let $\mathcal{T}_D$ be the set of all plane spanning trees on $D$ and $\mathcal{F}(\mathcal{T}_D)$ be the compatibility…

Let $G$ be a graph with adjacency matrix $A(G)$ and degree matrix $D(G)$, and let $L_\mu(G):=A(G)-\mu D(G)$. Two graphs $G_1$ and $G_2$ are called \emph{degree-similar} if there exists an invertible matrix $M$ such that $M^{-1} A(G_1) M…

Combinatorics · Mathematics 2025-09-03 Yi-Zheng Fan , Ruo-Jie Xing , Yi-Liu Zhang , Wei Wang

We investigate the terminal-pairibility problem in the case when the base graph is a complete bipartite graph, and the demand graph is also bipartite with the same color classes. We improve the lower bound on maximum value of $\Delta(D)$…

Combinatorics · Mathematics 2020-04-22 Lucas Colucci , Péter L. Erdős , Ervin Győri , Tamás Róbert Mezei

A plane topological graph $G=(V,E)$ is a graph drawn in the plane whose vertices are points in the plane and whose edges are simple curves that do not intersect, except at their endpoints. Given a plane topological graph $G=(V,E)$ and a set…

Computational Geometry · Computer Science 2020-07-24 J. C. Catana , A. García , J. Tejel , J. Urrutia

Let $F_G(P)$ be a functional defined on the set of all the probability distributions on the vertex set of a graph $G$. We say that $G$ is \emph{symmetric with respect to $F_G(P)$} if the uniform distribution on $V(G)$ maximizes $F_G(P)$.…

Combinatorics · Mathematics 2015-10-07 Seyed Saeed Changiz Rezaei , Ehsan Chiniforooshan

Based on the construction of polytope functions and several results about them in [LP], we take a deep look on their mutation behaviors to find a link between a face of a polytope and a sub-cluster algebra of the corresponding cluster…

Combinatorics · Mathematics 2024-06-06 Jie Pan

We prove that the proper amalgam of matroids $M_1$ and $M_2$ along their common restriction $N$ exists if and only if the tropical fibre product of Bergman fans ${B(M_1) \times_{B(N)} B(M_2)}$ is positive. We introduce tropical…

Algebraic Geometry · Mathematics 2024-04-30 Dmitry Mineev

Let $G$ be a cubic graph and $\Pi$ be a polyhedral embedding of this graph. The extended graph, $G^{e},$ of $\Pi$ is the graph whose set of vertices is $V(G^{e})=V(G)$ and whose set of edges $E(G^{e})$ is equal to $E(G) \cup \mathcal{S}$,…

Combinatorics · Mathematics 2019-11-28 Flor Aguilar , Gabriela Araujo-Pardo , Natalia García-Colín