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We apply results of Harada, Holm and Henriques to prove that the Atiyah-Segal equivariant complex $K$-theory ring of a divisive weighted projective space (which is singular for nontrivial weights) is isomorphic to the ring of integral…

Algebraic Topology · Mathematics 2015-02-10 Megumi Harada , Tara S. Holm , Nigel Ray , Gareth Williams

We extend the Gordon-Litherland pairing to links in thickened surfaces, and use it to define signature, determinant, and nullity invariants for links that bound (unoriented) spanning surfaces. The invariants are seen to depend only on the…

Geometric Topology · Mathematics 2023-01-12 Hans U. Boden , Micah Chrisman , Homayun Karimi

For a finite group $G$, we define an equivariant cobordism category $\mathcal{C}_d^G$. Objects of the category are $(d-1)$-dimensional closed smooth $G$-manifolds and morphisms are smooth $d$-dimensional equivariant cobordisms. We identify…

Algebraic Topology · Mathematics 2022-03-25 Gergely Szűcs , Søren Galatius

We provide a complete characterization of the equivariant commutative ring structures of all the factors in the idempotent splitting of the G-equivariant sphere spectrum, including their Hill-Hopkins-Ravenel norms, where G is any finite…

Algebraic Topology · Mathematics 2019-05-01 Benjamin Böhme

Given an orbifold, we construct an orthogonal spectrum representing its stable global homotopy type. Orthogonal spectra now represent orbifold cohomology theories which automatically satisfy certain properties as additivity and the…

Algebraic Topology · Mathematics 2025-12-24 Branko Juran

We study the $K$-theory and Swan theory of the group ring $R[G]$, when $G$ is a finite group and $R$ is any ring or ring spectrum. In this setting, the well-known assembly map for $K(R[G])$ has a companion called the coassembly map. We…

Algebraic Topology · Mathematics 2016-11-24 Cary Malkiewich

The ring of Witt vectors $\mathbb{W} R$ over a base ring $R$ is an important tool in algebraic number theory and lies at the foundations of modern $p$-adic Hodge theory. $\mathbb{W} R$ has the interesting property that it constructs a ring…

Logic in Computer Science · Computer Science 2020-12-24 Johan Commelin , Robert Y. Lewis

In this paper, we study Hamiltonian R-actions on symplectic orbifolds [M/S], where R and S are tori. We prove an injectivity theorem and generalize Tolman-Weitsman's proof of the GKM theorem in this setting. The main example is the…

Symplectic Geometry · Mathematics 2012-06-13 Tara Holm , Tomoo Matsumura

Equivariant complex $K$-theory and the equivariant sphere spectrum are two of the most fundamental equivariant spectra. For an odd $p$-group, we calculate the zeroth homotopy Green functor of the localization of the equivariant sphere…

Algebraic Topology · Mathematics 2022-04-27 Peter J. Bonventre , Bertrand J. Guillou , Nathaniel J. Stapleton

We introduce generalizations of global equivariant spectra which encode globally equivariant cohomology theories equipped with additional transfers, such as the deflation maps present in equivariant topological $K$-theory. We call these…

Algebraic Topology · Mathematics 2026-03-19 William Balderrama , Jack Morgan Davies , Sil Linskens

We provide a generalization of the construction of a spectrum of a commutative ring as a locally ringed space, applicable to cone injectivity classes in general contexts, especially in locally finitely presentable categories. In its full…

Category Theory · Mathematics 2023-12-05 Jan Jurka , Tomáš Perutka , Lukáš Vokřínek

Suppose that G is a finite, unitary reflection group acting on a complex vector space V and X is the fixed point subspace of an element of G. Define N to be the setwise stabilizer of X in G, Z to be the pointwise stabilizer, and C=N/Z. Then…

Representation Theory · Mathematics 2016-11-22 Nils Amend , Angela Berardinelli , J. Matthew Douglass , Gerhard Roehrle

In this paper we pursue the study of spectral categories initiated in [26]. More precisely, we construct the Universal matrix invariant of spectral categories, i.e. a functor U with values in an additive category Add, which inverts the…

Algebraic Topology · Mathematics 2009-04-15 Goncalo Tabuada

We prove a splitting result in global equivariant homotopy theory that is a simultaneous refinement of the Segal--Becker splitting and its `Real' and equivariant generalizations, and of the explicit Brauer induction of Boltje and Symonds.…

Algebraic Topology · Mathematics 2026-03-19 Stefan Schwede

We define a new invariant of finitely generated representations of a finite group, with coefficients in a commutative noetherian ring. This invariant uses group cohomology and takes values in the singularity category of the coefficient…

Representation Theory · Mathematics 2024-09-10 Paul Balmer , Martin Gallauer

Segal's Gamma-rings provide a natural framework for absolute algebraic geometry. We use Almkvist's global Witt construction to explore the relation with J. Borger F1-geometry and compute the Witt functor-ring of Almkvist for the simplest…

Algebraic Geometry · Mathematics 2020-04-21 Alain Connes , Caterina Consani

We give a simple construction of the correspondence between square-zero extensions $R'$ of a ring $R$ by an $R$-bimodule $M$ and second MacLane cohomology classes of $R$ with coefficients in $M$ (the simplest non-trivial case of the…

K-Theory and Homology · Mathematics 2015-10-23 D. Kaledin

We prove that Real topological Hochschild homology can be characterized as the norm from the cyclic group of order $2$ to the orthogonal group $O(2)$. From this perspective, we then prove a multiplicative double coset formula for the…

Algebraic Topology · Mathematics 2026-02-18 Gabriel Angelini-Knoll , Teena Gerhardt , Michael A. Hill

We approach a problem of realising algebraic objects in a certain universal equivariant stable homotopy theory; the global homotopy theory of Schwede. Specifically, for a global ring spectrum $R$, we consider which classes of ring…

Algebraic Topology · Mathematics 2021-08-31 Jack Morgan Davies

For any connected reductive group $G$ over $\mathbb{C}$, we revisit Goresky-Kottwitz-MacPherson's description of the torus equivariant Borel-Moore homology of affine Springer fibers $\mathrm{Sp}_\gamma\subset \mathrm{Gr}_G$, where…

Algebraic Geometry · Mathematics 2019-09-10 Oscar Kivinen
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