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We define a "circle Euler characteristic" of a circle action on a compact manifold or finite complex X. It lies in the first Hochschild homology group of ZG where G is the fundamental group of X. It is analogous in many ways to the ordinary…

K-Theory and Homology · Mathematics 2007-05-23 Ross Geoghegan , Andrew Nicas

We apply the equivariant Burnside group formalism to distinguish linear actions of finite groups, up to equivariant birationality. Our approach is based on De Concini-Procesi models of subspace arrangements.

Algebraic Geometry · Mathematics 2021-08-03 Andrew Kresch , Yuri Tschinkel

Equivariant versions of the radial index and of the GSV-index of a vector field or a 1-form on a singular variety with an action of a finite group are defined. They have values in the Burnside ring of the group. Poincar\'e-Hopf type…

Algebraic Geometry · Mathematics 2013-07-09 Wolfgang Ebeling , Sabir M. Gusein-Zade

We define Euler characteristic of a category enriched by a monoidal model category. If a monoidal model category V is equipped with Euler characteristic that is compatible with weak equivalences and fibrations in V, then our Euler…

Category Theory · Mathematics 2016-11-25 Kazunori Noguchi , Kohei Tanaka

We give explicit computations of the $\Gamma$-Euler characteristic of several families of orbit space definable translation groupoids. These include the translation groupoids associated to finite-dimensional linear representations of the…

Algebraic Topology · Mathematics 2025-08-27 Carla Farsi , Hannah Mobley , Christopher Seaton

By the work of J.Huh, one can interpret binomial coefficients as a solution to an intersection problem on a permutohedral variety $X_E$. Applying Hirzebruch-Riemann-Roch, this intersection problem is equivalent to computing Euler…

Algebraic Geometry · Mathematics 2025-10-16 Vincenzo Galgano , Hanieh Keneshlou , Mateusz Michalek

We introduce equivariant Burnside groups, new invariants in equivariant birational geometry, generalizing birational symbols groups for actions of finite abelian groups, due to Kontsevich, Pestun, and the second author, and study their…

Algebraic Geometry · Mathematics 2020-07-27 Andrew Kresch , Yuri Tschinkel

The Euler form is an Ext analog of the Euler characteristic, and in this paper we study the Euler form and give some applications. The first being a question of Jorgensen, which bounds the projective dimension of a module over a complete…

Commutative Algebra · Mathematics 2025-04-10 Benjamin Katz , Andrew J. Soto Levins

We discuss the universal orbifold Euler characteristic and generalized orbifold Euler characteristics corresponding to finitely generated groups $A$ (the $A$-Euler characteristics). We show that the collection of all $A$-Euler…

Algebraic Geometry · Mathematics 2024-05-15 Sabir M. Gusein-Zade , Ignacio Luengo , Alejandro Melle-Hernández , Antonio Viruel

After we have given a survey on the Burnside ring of a finite group, we discuss and analyze various extensions of this notion to infinite (discrete) groups. The first three are the finite-G-set-version, the inverse-limit-version and the…

Algebraic Topology · Mathematics 2007-05-23 Wolfgang Lueck

We determine all the equivariant Euler characteristics of the building for the general unitary group over a finite field.

Combinatorics · Mathematics 2020-03-18 Jesper M. Møller

For a discrete group $\Gamma$ satisfying some finiteness conditions we give a Bredon projective resolution of the trivial module in terms of projective covers of the chain complex associated to certain posets of subgroups. We use this to…

Group Theory · Mathematics 2012-02-27 Conchita Martínez-Pérez

B\'ezout's theorem, nonequivariantly, can be interpreted as a calculation of the Euler class of a sum of line bundles over complex projective space, expressing it in terms of the rank of the bundle and its degree. We give here a…

Algebraic Topology · Mathematics 2024-07-24 Steven R. Costenoble , Thomas Hudson , Sean Tilson

The variational properties of the scalar so--called ``Universal'' equations are reviewed and generalised. In particular, we note that contrary to earlier claims, each member of the Euler hierarchy may have an explicit field dependence. The…

High Energy Physics - Theory · Physics 2008-11-26 J. A. Mulvey

We define notions of higher order spectra of a complex quasi-projective manifold with an action of a finite group $G$ and with a $G$-equivariant automorphism of finite order, some of their refinements and give Macdonald type equations for…

Algebraic Geometry · Mathematics 2015-07-30 Wolfgang Ebeling , Sabir M. Gusein-Zade

Let G be a finite group and let M be a G-manifold. We introduce the concept of generalized orbifold invariants of M/G associated to an arbitrary group Gamma, an arbitrary Gamma-set, and an arbitrary covering space of a connected manifold…

Group Theory · Mathematics 2014-10-01 Hirotaka Tamanoi

We assign to a finite $CW$-complex and an element in its first cohomology group a twisted version of the $L^2$-Euler characteristic and study its main properties. In the case of an irreducible orientable $3$-manifold with empty or toroidal…

Geometric Topology · Mathematics 2018-10-03 Stefan Friedl , Wolfgang Lück

Let f be a C1 bivariate function with Lipschitz derivatives, and F = {x $\in$ R2 : f(x) $\lambda$} an upper level set of f, with $\lambda$ $\in$ R. We present a new identity giving the Euler characteristic of F in terms of its three-points…

Probability · Mathematics 2018-12-10 Raphaël Lachièze-Rey

Orbifold equivalence is a notion of symmetry that does not rely on group actions. Among other applications, it leads to surprising connections between hitherto unrelated singularities. While the concept can be defined in a very general…

Quantum Algebra · Mathematics 2017-08-29 Andreas Recknagel , Paul Weinreb

If a real value invariant of compact combinatorial manifolds (with or without boundary) depends only on the number of simplices in each dimension on the manifold, then the invariant is completely determined by Euler characteristics of the…

Geometric Topology · Mathematics 2011-01-25 Li Yu