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We introduce the universal Euler characteristic of orbit space definable groupoids, a class of groupoids containing cocompact proper Lie groupoids as well as translation groupoids associated to proper definable group actions. We show that…

Differential Geometry · Mathematics 2025-07-22 Carla Farsi , Emily Proctor , Christopher Seaton

We geometrically construct a homology theory that generalizes the Euler characteristic mod 2 to objects in the unoriented cobordism ring N_*(X) of a topological space X. This homology theory Eh_* has coefficients Z/2 in every nonnegative…

Algebraic Topology · Mathematics 2007-05-23 Julia Weber

Since the introduction of the Hermitian adjacency matrix for digraphs, interest in so-called complex unit gain graphs has surged. In this work, we consider gain graphs whose spectra contain the minimum number of two distinct eigenvalues.…

Combinatorics · Mathematics 2021-05-20 Pepijn Wissing , Edwin R. van Dam

We consider the problem of computing the Euler characteristic of an abstract simplicial complex given by its vertices and facets. We show that this problem is #P-complete and present two new practical algorithms for computing Euler…

Computational Geometry · Computer Science 2011-12-21 Bjarke Hammersholt Roune , Eduardo Sáenz de Cabezón

We study three mixing properties of a graph: large algebraic connectivity, large Cheeger constant (isoperimetric number) and large spectral gap from 1 for the second largest eigenvalue of the transition probability matrix of the random walk…

Combinatorics · Mathematics 2013-12-17 Mikhail Isaev , K. V Isaeva

In this paper, we introduce a way to generalize the Euler's gamma function as well as some related special functions. With a given polynomial in one variable $f(t)\ge 0$, we can associate a function, so-called "gamma function associated…

Complex Variables · Mathematics 2011-05-31 Tran Gia Loc , Trinh Duc Tai

To every tree we associate a filtered cochain complex. Its cohomology and the corresponding spectral sequence have clear combinatorial description. If a tree is the Dynkin diagram of a simple plane curve singularity, the graded Euler…

Combinatorics · Mathematics 2009-01-12 E. Gorsky

Hypergraph is a topological model for networks. In order to study the topology of hypergraphs, the homology of the associated simplicial complexes and the embedded homology have been invented. In this paper, we give some algorithms to…

Algebraic Topology · Mathematics 2018-01-03 Shiquan Ren , Chengyuan Wu , Stephane Bressan , Jie Wu

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

A representation of the perturbation series of a general functional measure is given in terms of generalized Feynman graphs and -rules. The graphical calculus is applied to certain functional measures of L\'evy type. A graphical notion of…

Mathematical Physics · Physics 2007-05-23 S. H. Djah , H. Gottschalk , H. Ouerdiane

We investigate combinatorial properties of a graph polynomial indexed by half-edges of a graph which was introduced recently to understand the connection between Feynman rules for scalar field theory and Feynman rules for gauge theory. We…

Combinatorics · Mathematics 2012-07-24 Dirk Kreimer , Karen Yeats

For any graph G we define bigraded cohomology groups whose graded Euler characteristic is a multiple of the Yamada polynomial of G.

Geometric Topology · Mathematics 2012-02-20 V. Vershinin , A. Vesnin

The aim of this paper is to derive on the basis of the Euler's formula several analytical relations which hold for certain classes of planar graphs and which can be useful in algorithmic graph theory.

Discrete Mathematics · Computer Science 2012-07-11 Armen Bagdasaryan

Under suitable conditions, we show that the Euler characteristic of a foliated Riemannian manifold can be computed only from curvature invariants which are transverse to the leaves. Our proof uses the hypoelliptic sub-Laplacian on forms…

Differential Geometry · Mathematics 2021-06-30 Fabrice Baudoin , Erlend Grong , Gianmarco Vega-Molino

A computer program has been developed which generates Feynman graphs automatically for scattering and decay processes in non-Abelian gauge theory of high-energy physics. A new acceleration method is presented for both generating and…

High Energy Physics - Theory · Physics 2009-10-28 Toshiaki Kaneko

The idea of graph compositions, which was introduced by A. Knopfmacher and M. E. Mays, generalizes both ordinary compositions of positive integers and partitions of finite sets. In their original paper they developed formulas, generating…

Combinatorics · Mathematics 2007-05-23 Aminul Huq

This paper provides the generating series for the embedding of tree-like graphs of arbitrary number of vertices, accourding to their genus. It applies and extends the techniques of Chan, where it was used to give an alternate proof of the…

Combinatorics · Mathematics 2017-02-10 Aaron Chun Shing Chan

The Euler genus of a graph is a fundamental and well-studied parameter in graph theory and topology. Computing it has been shown to be NP-hard by [Thomassen '89 & '93], and it is known to be fixed-parameter tractable. However, the…

Data Structures and Algorithms · Computer Science 2013-11-04 Chandra Chekuri , Anastasios Sidiropoulos

A seminal technique of theoretical physics called Wick's theorem interprets the Gaussian matrix integral of the products of the trace of powers of Hermitian matrices as the number of labelled maps with a given degree sequence, sorted by…

Combinatorics · Mathematics 2009-06-09 Mihyun Kang , Martin Loebl

The topology and geometry of random fields - in terms of the Euler characteristic and the Minkowski functionals - has received a lot of attention in the context of the Cosmic Microwave Background (CMB), as the detection of primordial…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-02 Job Feldbrugge , Matti van Engelen , Rien van de Weygaert , Pratyush Pranav , Gert Vegter
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