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We use the equivariant cohomology ring of the permutohedral variety to study matroids and their invariants. Investigating the pushforward of matroid Chern classes defined by A. Berget, C. Eur, H. Spink and D. Tseng to the product space…

Algebraic Geometry · Mathematics 2025-09-25 Mario Bauer , Matěj Doležálek , Magdaléna Mišinová , Semen Słobodianiuk , Julian Weigert

Given a graph $G$, its genus polynomial is $\Gamma_G(x) = \sum_{k\geq 0} g_k(G)x^k$, where $g_k(G)$ is the number of 2-cell embeddings of $G$ in an orientable surface of genus $k$. The Log-Concavity Genus Distribution (LCGD) Conjecture…

Combinatorics · Mathematics 2022-12-21 MacKenzie Carr , Varpreet Dhaliwal , Bojan Mohar

Morphisms of matroids are combinatorial abstractions of linear maps and graph homomorphisms. We introduce the notion of basis for morphisms of matroids, and show that its generating function is strongly log-concave. As a consequence, we…

Combinatorics · Mathematics 2020-04-02 Christopher Eur , June Huh

For a graph G embedded in an orientable surface \Sigma, we consider associated links L(G) in the thickened surface \Sigma \times I. We relate the HOMFLY polynomial of L(G) to the recently defined Bollobas-Riordan polynomial of a ribbon…

Combinatorics · Mathematics 2012-03-01 Iain Moffatt

The "2-variable general-$\lambda$-matrix polynomials (2VG$\lambda$MP)" is a new family of matrix polynomials, introduced and studied in this article. These matrix polynomials are constructed using umbral and symbolic methods. We delve into…

Classical Analysis and ODEs · Mathematics 2024-12-03 Ghazala Yasmin , Aditi Sharma

We find new properties of the topological transition polynomial of embedded graphs, $Q(G)$. We use these properties to explain the striking similarities between certain evaluations of Bollob\'as and Riordan's ribbon graph polynomial,…

Combinatorics · Mathematics 2014-06-10 Joanna A. Ellis-Monaghan , Iain Moffatt

In 1977, Yu. V. Matiyasevich proposed a formula expressing the chromatic polynomial of an arbitrary graph as a linear combination of flow polynomials of subgraphs of the original graph. In this paper, we prove that this representation is a…

Combinatorics · Mathematics 2024-06-17 E. Yu. Lerner

A k-valuation is a special type of edge k-colouring of a medial graph. Various graph polynomials, such as the Tutte, Penrose, Bollob\'as-Riordan, and transition polynomials, admit combinatorial interpretations and evaluations as weighted…

Combinatorics · Mathematics 2018-07-20 Joanna A. Ellis-Monaghan , Louis H. Kauffman , Iain Moffatt

This paper revisits spectral graph convolutional neural networks (graph-CNNs) given in Defferrard (2016) and develops the Laplace-Beltrami CNN (LB-CNN) by replacing the graph Laplacian with the LB operator. We then define spectral filters…

Machine Learning · Computer Science 2020-10-27 Shih-Gu Huang , Moo K. Chung , Anqi Qiu , Alzheimer's Disease Neuroimaging Initiative

The Tutte polynomial is an important invariant of graphs and matroids. Chen and Guo \emph{[Adv. in Appl. Math. 166 (2025) 102868.]} proved that for a $(k+1)$-edge connected graph $G$ and for any $i$ with $0\leq i <\frac{3(k+1)}{2}$,…

Combinatorics · Mathematics 2025-09-29 Xiaxia Guan , Xian'an Jin , Tianlong Ma , Weihua Yang

The study of (minimally) rigid graphs is motivated by numerous applications, mostly in robotics and bioinformatics. A major open problem concerns the number of embeddings of such graphs, up to rigid motions, in Euclidean space. We capture…

Computational Geometry · Computer Science 2009-08-27 Ioannis Z. Emiris , Elias P. Tsigaridas , Antonios Varvitsiotis

Motivated by circle graphs, and the enumeration of Euler circuits, we define a one-variable ``interlace polynomial'' for any graph. The polynomial satisfies a beautiful and unexpected reduction relation, quite different from the cut and…

Combinatorics · Mathematics 2007-05-23 Richard Arratia , Bela Bollobas , Gregory B. Sorkin

In this article we present theoretical and computational results on the existence of polyhedral embeddings of graphs. The emphasis is on cubic graphs. We also describe an efficient algorithm to compute all polyhedral embeddings of a given…

Combinatorics · Mathematics 2023-06-22 Gunnar Brinkmann , Thomas Tucker , Nico Van Cleemput

The Tutte polynomial and Derksen's $\mathcal{G}$-invariant are the universal deletion-contraction and valuative matroid and polymatroid invariants, respectively. There are only a handful of well known invariants (like the matroid…

Combinatorics · Mathematics 2025-05-16 Max Wakefield

We consider the two-variable interlace polynomial introduced by Arratia, Bollobas and Sorkin (2004). We develop graph transformations which allow us to derive point-to-point reductions for the interlace polynomial. Exploiting these…

Computational Complexity · Computer Science 2008-04-16 Markus Bläser , Christian Hoffmann

Given a graph $G$, the maximal induced subgraphs problem asks to enumerate all maximal induced subgraphs of $G$ that belong to a certain hereditary graph class. While its optimization version, known as the minimum vertex deletion problem in…

Data Structures and Algorithms · Computer Science 2020-04-22 Yixin Cao

The $2$-cell embeddings of graphs on closed surfaces have been widely studied. It is well known that ($2$-cell) embedding a given graph $G$ on a closed orientable surface is equivalent to cyclically ordering the edges incident to each…

Combinatorics · Mathematics 2015-03-06 Ricky X. F. Chen , Christian M. Reidys

This paper considers the problem of embedding directed graphs in Euclidean space while retaining directional information. We model a directed graph as a finite set of observations from a diffusion on a manifold endowed with a vector field.…

Machine Learning · Statistics 2014-06-03 Dominique Perrault-Joncas , Marina Meila

In an $\mathsf{L}$-embedding of a graph, each vertex is represented by an $\mathsf{L}$-segment, and two segments intersect each other if and only if the corresponding vertices are adjacent in the graph. If the corner of each…

Computational Geometry · Computer Science 2017-03-07 Abu Reyan Ahmed , Felice De Luca , Sabin Devkota , Alon Efrat , Md Iqbal Hossain , Stephen Kobourov , Jixian Li , Sammi Abida Salma , Eric Welch

The Tutte polynomial is a significant invariant of graphs and matroids. It is well-known that it has three equivalent definitions: bases expansion, rank generating function, and deletion-contraction formula. The polymatroid Tutte polynomial…

Combinatorics · Mathematics 2025-10-14 Xiaxia Guan , Xian'an Jin , Weiling Yang