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Related papers: Compactly supported $\mathbb{A}^{1}$-Euler charact…

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We show that for a reductive group $G$ over a field $k$ the $\mathbb{A}^1$-Euler characteristic of the variety of maximal tori in $G$ is an invertible element of the Grothendieck-Witt ring $\mathrm{GW}(k)$, settling the weak form of a…

Algebraic Geometry · Mathematics 2021-05-25 Alexey Ananyevskiy

For a finitely presented discrete group $\Gamma$, we introduce two generalizations of the orbifold Euler characteristic and $\Gamma$-orbifold Euler characteristic to a class of proper topological groupoids large enough to include all…

Algebraic Topology · Mathematics 2022-10-19 Carla Farsi , Christopher Seaton

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 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

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

It is well known that the Euler characteristic of an odd dimensional compact manifold is zero. An Euler complex is a combinatorial analogue of a compact manifold. We present here an elementary proof of the corresponding result for Euler…

Geometric Topology · Mathematics 2013-02-25 Colin MacLaurin , Guyan Robertson

In this article we formulate and prove the main theorems of the theory of character sheaves on unipotent groups over an algebraically closed field of characteristic p>0. In particular, we show that every admissible pair for such a group G…

Representation Theory · Mathematics 2013-01-08 Mitya Boyarchenko , Vladimir Drinfeld

We evaluate the Geiss-Leclerc-Schroer $\phi$-map for shape modules over the preprojective algebra $\Lambda$ of type $\hat{A_1}$ in terms of matrix minors arising from the block-Toeplitz representation of the loop group $\SL_2(\mathcal{L})$.…

Representation Theory · Mathematics 2007-07-23 Jeanne Scott

We construct, for any symplectic, unitary or special orthogonal group over a locally compact nonarchimedean local field of odd residual characteristic, a type for each Bernstein component of the category of smooth representations, using…

Representation Theory · Mathematics 2012-12-04 Michitaka Miyauchi , Shaun Stevens

The apparatus of motivic stable homotopy theory provides a notion of Euler characteristic for smooth projective varieties, valued in the Grothendieck-Witt ring of the base field. Previous work of the first author and recent work of…

Algebraic Geometry · Mathematics 2020-08-26 Marc Levine , Arpon Raksit

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

Let X be an algebraic projective variety in {\bf P}^n. Denote by {\cal C}_{\lambda} the space of all effective cycles on X whose homology class is \lambda \in H_{2p} (X,{\bf Z}). It is easy to show that {\cal C}_{\lambda} is an algebraic…

alg-geom · Mathematics 2008-02-03 Javier Elizondo

This note studies the behavior of Euler characteristics and of intersection homology Euler characterstics under proper morphisms of algebraic (or analytic) varieties. The methods also yield, for algebraic (or analytic) varieties, formulae…

Algebraic Topology · Mathematics 2012-04-03 Sylvain E. Cappell , Laurentiu Maxim , Julius L. Shaneson

We give an elementary proof of the fact that a pure-dimensional closed subvariety of a complex abelian variety has a signed intersection homology Euler characteristic. We also show that such subvarieties which, moreover, are local complete…

Algebraic Topology · Mathematics 2018-04-24 Eva Elduque , Christian Geske , Laurentiu Maxim

Using the weak factorization theorem we give a simple presentation for the value group of the universal Euler characteristic with compact support for varieties of characteristic zero and describe the value group of the universal Euler…

Algebraic Geometry · Mathematics 2007-05-23 Franziska Bittner

We compute the weighted Euler characteristic, equivariant with respect to the action of the symplectic group of degree six over the field of two elements, of the moduli space of principally polarized abelian threefolds together with a level…

Algebraic Geometry · Mathematics 2018-04-26 Jonas Bergström , Olof Bergvall

It is shown that the Euler characteristic $\chi_{(\mathcal{H},\mathcal{B},\epsilon_q)}$ of a $\mathbb{Z}[[q]]$-Hecke algebra $\mathcal{H}$ associated with a finitely generated Coxeter group $(W,S)$ coincides with $p_{(W,S)}(q)^{-1}$, where…

Representation Theory · Mathematics 2014-05-26 T. Terragni , Th. Weigel

We prove an analogue of the Riemann-Hurwitz theorem for computing Euler characteristics of pullbacks of coherent sheaves through finite maps of smooth projective varieties, subject only to the condition that the irreducible components of…

Algebraic Geometry · Mathematics 2017-04-20 Andrew Fiori

Euler-symmetric projective varieties are nondegenerate projective varieties admitting many C*-actions of Euler type. They are quasi-homogeneous and uniquely determined by their fundamental forms at a general point. We show that…

Algebraic Geometry · Mathematics 2017-07-24 Baohua Fu , Jun-Muk Hwang

We apply the Atiyah-Singer index theorem and tensor products of elliptic complexes to the cohomology of transitive Lie algebroids. We prove that the Euler characteristic of a representation of a transitive Lie algebroid $A$ over a compact…

Differential Geometry · Mathematics 2019-08-20 James Waldron