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We determine the cohomology groups of the space of seven points in general linear position as representations of the symmetric group on seven elements by making equivariant point counts over finite fields. We also comment on the case of…

Algebraic Geometry · Mathematics 2020-08-03 Olof Bergvall

We extend the theory of equivariant orthogonal spectra from finite groups to profinite groups, and more generally from compact Lie groups to compact Hausdorff groups. The G-homotopy theory is "pieced together" from the G/U-homotopy theories…

Algebraic Topology · Mathematics 2014-11-11 Halvard Fausk

We construct Steinberg summands of $G$-equivariant spectra with $\mathrm{GL}_n(\mathbb{F}_p)$-action. We prove a lemma about their fixed points when $G$ is a $p$-group, and then use this lemma to compute the fixed points of the Steinberg…

Algebraic Topology · Mathematics 2019-03-21 Krishanu Sankar

We generalise the Atiyah-Segal-Singer fixed point theorem to noncompact manifolds. Using $KK$-theory, we extend the equivariant index to the noncompact setting, and obtain a fixed point formula for it. The fixed point formula is the…

K-Theory and Homology · Mathematics 2018-04-04 Peter Hochs , Hang Wang

If K is a discrete group and Z is a K-spectrum, then the homotopy fixed point spectrum Z^{hK} is Map_*(EK_+, Z)^K, the fixed points of a familiar expression. Similarly, if G is a profinite group and X is a discrete G-spectrum, then X^{hG}…

Algebraic Topology · Mathematics 2013-12-02 Daniel G. Davis

We establish an equivariant generalization of the Novikov inequalities which allow to estimate the topology of the set of critical points of a closed basic invariant form by means of twisted equivariant cohomology of the manifold. We apply…

dg-ga · Mathematics 2008-02-03 M. Braverman , M. Farber

We define persistent homology groups over any set of spaces which have inclusions defined so that the corresponding directed graph between the spaces is acyclic, as well as along any subgraph of this directed graph. This method…

Computational Geometry · Computer Science 2019-06-20 Erin Wolf Chambers , David Letscher

We compute the equivariant homology and cohomology of projective spaces with integer coefficients. More precisely, in the case of cyclic groups, we show that the cellular filtration of the projective space $P(k\rho )$, of lines inside…

Algebraic Topology · Mathematics 2025-09-24 Samik Basu , Pinka Dey , Aparajita Karmakar

In this paper we consider a class of connected closed $G$-manifolds with a non-empty finite fixed point set, each $M$ of which is totally non-homologous to zero in $M_G$ (or $G$-equivariantly formal), where $G={\Bbb Z}_2$. With the help of…

Algebraic Topology · Mathematics 2009-02-17 Bo Chen , Zhi Lü

In this paper, we introduce a symmetric continuous cohomology of topological groups. This is obtained by topologizing a recent construction due to Staic (J. Algebra 322 (2009), 1360-1378), where a symmetric cohomology of abstract groups is…

Group Theory · Mathematics 2013-06-04 Mahender Singh

Persistent homology is a popular and useful tool for analysing finite metric spaces, revealing features that can be used to distinguish sets of unlabeled points and as input into machine learning pipelines. The famous stability theorem of…

Computational Geometry · Computer Science 2024-05-10 Philip Smith , Vitaliy Kurlin

We want to compute generic $\mathrm{Ext}$-spaces of twisted polynomial functors in relation to the $\mathrm{Ext}$-spaces of the untwisted ones, modulo a parametrisation. Thanks to the study of a spectral sequence we get to a computation in…

Algebraic Topology · Mathematics 2026-01-28 Iacopo Giordano

We develop a new method to compute the homology groups of finite topological spaces (or equivalently of finite partially ordered sets) by means of spectral sequences giving a complete and simple description of the corresponding…

Algebraic Topology · Mathematics 2016-12-14 Nicolás Cianci , Miguel Ottina

The paper is devoted to homology groups of cubical sets with coefficients in contravariant systems of Abelian groups. The study is based on the proof of the assertion that the homology groups of the category of cubes with coefficients in…

Algebraic Topology · Mathematics 2023-07-06 Ahmet A. Husainov

We provided two explicit formulas for the intersection cohomology (as a graded vector space with pairing) of the symplectic quotient by a circle in terms of the $S^1$ equivariant cohomology of the original symplectic manifold and the fixed…

Differential Geometry · Mathematics 2007-05-23 Eugene Lerman , Susan Tolman

The cohomology of a tiling or a point pattern has originally been defined via the construction of the hull or the groupoid associated with the tiling or the pattern. Here we present a construction which is more direct and therefore easier…

Mathematical Physics · Physics 2009-11-07 Johannes Kellendonk

We compute the trace of an endomorphism in equivariant bivariant K-theory for a compact group G in several ways: geometrically using geometric correspondences, algebraically using localisation, and as a Hattori-Stallings trace. This results…

K-Theory and Homology · Mathematics 2015-10-23 Ivo Dell'Ambrogio , Heath Emerson , Ralf Meyer

We use sheaf theory and the six operations to define and study the (equivariant) homology of stacks. The construction makes sense in the algebraic, complex-analytic, or even topological categories.

Algebraic Topology · Mathematics 2025-06-06 Adeel A. Khan

In this note we prove an equivariant version of a result of Cartan for equivariant simplicial cohomology with local coefficients.

Algebraic Topology · Mathematics 2010-03-19 Debasis Sen

Using the method of equivariant moving frames, we present a procedure for constructing symmetry-preserving finite element methods for second-order ordinary differential equations. Using the method of lines, we then indicate how our…

Numerical Analysis · Mathematics 2018-03-28 Alexander Bihlo , Francis Valiquette