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The Poupard polynomials are polynomials in one variable with integer coefficients, with some close relationship to Bernoulli and tangent numbers. They also have a combinatorial interpretation. We prove that every Poupard polynomial has all…

Combinatorics · Mathematics 2020-01-07 Frédéric Chapoton , Guo-Niu Han

We define a class of bipartite graphs that correspond naturally with Ferrers diagrams. We give expressions for the number of spanning trees, the number of Hamiltonian paths when applicable, the chromatic polynomial, and the chromatic…

Combinatorics · Mathematics 2007-06-21 Richard Ehrenborg , Stephanie van Willigenburg

This is a note on three graph parameters motivated by the Euler-Poincare characteristic for simplicial complex. We show those three graph parameters of a given connected graph $G$ is greater than or equal to that of the complete graph with…

Combinatorics · Mathematics 2012-11-28 Hanbaek Lyu

In this paper, we introduce a new concept namely degree polynomial for vertices of a simple graph. This notion leads to a concept namely degree polynomial sequence which is stronger than the concept of degree sequence. After obtaining the…

Combinatorics · Mathematics 2020-09-02 Reza Jafarpour-Golzari

We introduce a new cohomology theory for planar trivalent graphs with perfect matchings. The graded Euler characteristic of the cohomology is a one variable polynomial called the 2-factor polynomial that, if nonzero when evaluated at one,…

Geometric Topology · Mathematics 2023-03-15 Scott Baldridge

We define pure graphs, invertible graphs, and the notion of complementation of bicoloured graphs. The study of pure graphs is motivated by two conjectures about the transition systems of eulerian graphs and by the Cycle Double Cover…

Combinatorics · Mathematics 2007-05-23 François Genest

We introduce a new graph polynomial that encodes interesting properties of graphs, for example, the number of matchings and the number of perfect matchings. Most importantly, for bipartite graphs the polynomial encodes the number of…

Discrete Mathematics · Computer Science 2010-02-10 Qi Ge , Daniel Stefankovic

This paper surveys a comprehensive, although not exhaustive, sampling of graph polynomials with the goal of providing a brief overview of a variety of techniques defining a graph polynomial and then for decoding the combinatorial…

Combinatorics · Mathematics 2008-07-01 Joanna Ellis-Monaghan , Criel Merino

We compute an analogue of Pascal's triangle enriched in bilinear forms over a finite field. This gives an arithmetically meaningful count of the ways to choose $j$ ring homomorphisms into an algebraic closure from an \'etale extension of…

Number Theory · Mathematics 2026-01-12 Chongyao Chen , Kirsten Wickelgren

Recently, Benedetti et al. introduced an Ehrhart-like polynomial associated to a graph. This polynomial is defined as the volume of a certain flow polytope related to a graph and has the property that the leading coefficient is the volume…

Combinatorics · Mathematics 2019-11-26 Jihyeug Jang , Jang Soo Kim

The Hosoya polynomial of a graph encompasses many of its metric properties, for instance the Wiener index (alias average distance) and the hyper-Wiener index. An expression is obtained that reduces the computation of the Hosoya polynomials…

Combinatorics · Mathematics 2012-12-14 Emeric Deutsch , Sandi Klavzar

We consider a graph polynomial \xi(G;x,y,z) introduced by Averbouch, Godlin, and Makowsky (2007). This graph polynomial simultaneously generalizes the Tutte polynomial as well as a bivariate chromatic polynomial defined by Dohmen, Poenitz…

Combinatorics · Mathematics 2008-01-11 Christian Hoffmann

In 1979 Frankl conjectured that in a finite non-trivial union-closed collection of sets there has to be an element that belongs to at least half the sets. We show that this is equivalent to the conjecture that in a finite non-trivial graph…

Combinatorics · Mathematics 2013-05-17 Henning Bruhn , Pierre Charbit , Oliver Schaudt , Jan Arne Telle

To a singular knot K with n double points, one can associate a chord diagram with n chords. A chord diagram can also be understood as a 4-regular graph endowed with an oriented Euler circuit. L. Traldi introduced a polynomial invariant for…

Combinatorics · Mathematics 2025-09-23 Alexander Dunaykin , Vyacheslav Zhukov

In this article, the enumeration of partial chord diagrams is discussed via matrix model techniques. In addition to the basic data such as the number of backbones and chords, we also consider the Euler characteristic, the backbone spectrum,…

In this paper, we find computational formulae for generalized characteristic polynomials of graph bundles. We show that the number of spanning trees in a graph is the partial derivative (at (0,1)) of the generalized characteristic…

Combinatorics · Mathematics 2008-07-03 Dongseok Kim , Hye Kyung Kim , Jaeun Lee

Binomial Cayley graphs are obtained by considering the binomial coefficient of the weight function of a given Cayley graph and a natural number. We introduce these objects and study two families: one associated with symmetric groups and the…

Combinatorics · Mathematics 2024-09-06 Bernat Bassols-Cornudella , Francesco Viganò

An efficient algorithm is presented to compute the characteristic polynomial of a threshold graph. Threshold graphs were introduced by Chv\'atal and Hammer, as well as by Henderson and Zalcstein in 1977. A threshold graph is obtained from a…

Data Structures and Algorithms · Computer Science 2015-03-03 Martin Fürer

A hole in a graph is an induced subgraph which is a cycle of length at least four. A graph is chordal if it contains no holes. Following McKee and Scheinerman (1993), we define the chordality of a graph $G$ to be the minimum number of…

Combinatorics · Mathematics 2024-04-10 Aristotelis Chaniotis , Babak Miraftab , Sophie Spirkl

We show that any graph polynomial from a wide class of graph polynomials yields a recurrence relation on an infinite class of families of graphs. The recurrence relations we obtain have coefficients which themselves satisfy linear…

Combinatorics · Mathematics 2013-09-17 Tomer Kotek , Johann A. Makowsky