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We develop a theory of umkehr maps for twisted generalized homology theories. In this theory, interesting umkehr maps, including generalizations of important classical ones, are induced by cartesian morphisms of a certain category opfibred…

Algebraic Topology · Mathematics 2026-03-30 Anssi Lahtinen

The Chern-Dold character of a cohomology theory E is a canonical transformation $E\rightarrow HV$ to ordinary cohomology. A spectrum representing E gives homotopy theoretic cocycles for E, while HV can be represented by singular cocycles.…

Algebraic Topology · Mathematics 2014-04-09 Markus Upmeier

We show that Shipley's "detection functor" for symmetric spectra generalizes to motivic symmetric spectra. As an application, we construct motivic strict ring spectra representing morphic cohomology, semi-topological $K$-theory, and…

Algebraic Geometry · Mathematics 2013-04-24 Jeremiah Heller

We prove excision in entire and periodic cyclic cohomology and construct a Chern-Connes character for Fredholm modules over a C*-algebra without summability restrictions, taking values in a variant of Connes's entire cyclic cohomology.…

K-Theory and Homology · Mathematics 2007-05-23 Ralf Meyer

This paper is our first step in establishing a de Rham model for equivariant twisted $K$-theory using machinery from noncommutative geometry. Let $G$ be a compact Lie group, $M$ a compact manifold on which $G$ acts smoothly. For any $\alpha…

K-Theory and Homology · Mathematics 2015-05-01 Jean-Louis Tu , Ping Xu

We examine the slice spectral sequence for the cohomology of singular schemes with respect to various motivic T-spectra, especially the motivic cobordism spectrum. When the base field k admits resolution of singularities and X is a scheme…

Algebraic Geometry · Mathematics 2018-12-26 Amalendu Krishna , Pablo Pelaez

We give a simple universal property of the multiplicative structure on the Thom spectrum of an $n$-fold loop map, obtained as a special case of a characterization of the algebra structure on the colimit of a lax $\mathcal{O}$-monoidal…

Algebraic Topology · Mathematics 2026-01-05 Omar Antolín-Camarena , Tobias Barthel

We use the symbol calculus for foliations developed in our previous paper to derive a cohomological formula for the Connes-Chern character of the semi-finite spectral triple. The same proof works for the Type I spectral triple of…

Geometric Topology · Mathematics 2018-04-20 Moulay-Tahar Benameur , James L. Heitsch

We provide a systematic approach to twisting differential KO-theory leading to a construction of the corresponding twisted differential Atiyah-Hirzebruch spectral sequence (AHSS). We relate and contrast the degree two and the degree one…

Algebraic Topology · Mathematics 2026-04-15 Daniel Grady , Hisham Sati

We continue the investigation of twisted homology theories in the context of dimension drop phenomena. This work unifies previous equivariant index calculations in twisted cyclic cohomology. We do this by proving the existence of the…

K-Theory and Homology · Mathematics 2011-11-28 Adam Rennie , Roger Senior

The collection $\frk{C}_3$ of all triples of commuting contractions forms a family in the sense of Agler, and so has an "optimal" model $\pd\frk{C}_3$ generated by its extremal elements. A given $T\in\frk{C}_3$ is extremal if every…

Functional Analysis · Mathematics 2016-10-20 Edward J. Timko

The aim of this note is to show that the generalized supertrace, constructed in another paper of the author, inducing an isomorphism between the Hochschild homology of a superalgebra and that of the superalgebra of square supermatrices of a…

K-Theory and Homology · Mathematics 2009-05-28 Paul A. Blaga

Let $X/K$ be a variety over a field, and $A/K$ an abelian variety. A regular homomorphism to $A$ (in codimension $i$) induces, for every smooth geometrically connected pointed $K$-scheme $(T,t_0)$ and every cycle class $Z \in CH^i(T\times…

Algebraic Geometry · Mathematics 2025-06-23 Jeff Achter , Sebastian Casalaina-Martin , Charles Vial

The initial motivation of this work was to give a topological interpretation of two-periodic twisted de-Rham cohomology which is generalizable to arbitrary coefficients. To this end we develop a sheaf theory in the context of locally…

Algebraic Topology · Mathematics 2012-10-12 Ulrich Bunke , Markus Spitzweck , Thomas Schick

Let X be a quasi-compact scheme, equipped with an open covering by affine schemes. A quasi-coherent sheaf on X gives rise, by taking sections over the covering sets, to a diagram of modules over the various coordinate rings. The resulting…

K-Theory and Homology · Mathematics 2010-07-30 Thomas Huettemann

Using symmetrized Grassmannians we give an algebraic geometric presentation, in the level of classifying spaces, of the Chern character and its relation to Chern classes. This allows one to define, for any projective variety $X$, a Chern…

Algebraic Topology · Mathematics 2019-06-28 Ralph L. Cohen , Paulo Lima-Filho

The cyclotomic trace provides a comparison of the algebraic K-theory spectrum and a pro-spectrum TR that is built from the cyclic fixed points of topological Hochschild homology. In a previous paper with Ib Madsen, we used this comparison…

Number Theory · Mathematics 2019-08-12 Lars Hesselholt

We develop a theory of generalized characters of local systems in $\infty$-categories, which extends classical character theory for group representations and, in particular, the induced character formula. A key aspect of our approach is…

Algebraic Topology · Mathematics 2025-06-04 Shachar Carmeli , Bastiaan Cnossen , Maxime Ramzi , Lior Yanovski

We introduce the notion of "covering homology" of a commutative ring spectrum with respect to certain families of coverings of topological spaces. The construction of covering homology is extracted from Bokstedt, Hsiang and Madsen's…

Algebraic Topology · Mathematics 2008-02-08 Morten Brun , Gunnar Carlsson , Bjorn Ian Dundas

I. Panin proved in the nineties that the algebraic K-theory of twisted projective homogeneous varieties can be expressed in terms of central simple algebras. Later, Merkurjev and Panin described the algebraic K-theory of toric varieties as…

Algebraic Geometry · Mathematics 2013-10-16 Goncalo Tabuada