27 citations · 76 across the 17 of their papers we have counts for
20 papers
A few computations about the real cycle class map in low dimensions
Jens Hornbostel
We investigate the surjectivity of the real cycle class map from -cohomology to classical intergral cohomology for some real smooth varieties, in particular surfaces. This might…
Real Topological Hochschild Homology of Perfectoid Rings
Jens Hornbostel, Doosung Park
We refine several results of Bhatt-Morrow-Scholze on THH to THR. In particular, we compute THR of perfectoid rings. This will be useful for establishing motivic filtrations on real…
Atiyah-Segal completion for the Hermitian K-theory of Symplectic Groups
Jens Hornbostel, Herman Rohrbach, Marcus Zibrowius
We study equivariant Hermitian K-theory for representations of symplectic groups, especially . The results are used to establish an Atiyah-Segal completion theorem f…
Real topological Hochschild homology of schemes
Jens Hornbostel, Doosung Park
We prove that real topological Hochschild homology THR for schemes with involution satisfies base change and descent for the Z/2-isovariant étale topology. As an application, we pr…
Formal ternary laws and Buchstaber's 2-groups
David Coulette, Frédéric Déglise, Jean Fasel +1
We develop the algebraic formalism of the formal ternary laws of C. Walter and we compare them to Buchstaber's 2-valued formal group laws. We also compute the "elementary" formal t…
The real cycle class map
Jens Hornbostel, Matthias Wendt, Heng Xie +1
The classical cycle class map for a smooth complex variety sends cycles in the Chow ring to cycles in the singular cohomology ring. We study two cycle class maps for smooth real va…
Chow-Witt rings of split quadrics
Jens Hornbostel, Heng Xie, Marcus Zibrowius
We compute the Chow-Witt rings of split quadrics over a field of characteristic not two. We even determine the full bigraded I-cohomology and Milnor-Witt cohomology rings, includin…
Chow-Witt rings of classifying spaces for symplectic and special linear groups
Jens Hornbostel, Matthias Wendt
We compute the Chow-Witt rings of the classifying spaces for the symplectic and special linear groups. In the structural description we give, contributions from real and complex re…
Smooth Schubert varieties and generalized Schubert polynomials in algebraic cobordism of Grassmannians
Jens Hornbostel, Nicolas Perrin
We provide several ingredients towards a generalization of the Littlewood-Richardson rule from Chow groups to algebraic cobordism. In particular, we prove a simple product-formula…
Some comments on motivic nilpotence
Jens Hornbostel
We discuss some results and conjectures related to the existence of the non-nilpotent motivic maps and . To this purpose, we establish a theory of power operations for mot…
Semistable Symmetric Spectra in -homotopy theory
Stephan Haehne, Jens Hornbostel
We study semistable symmetric spectra based on quite general monoidal model categories, including motivic examples. In particular, we establish a generalization of Schwede's list o…
Infinite CW-complexes, Brauer groups and phantom cohomology
Jens Hornbostel, Stefan Schroeer
Expanding a result of Serre on finite CW-complexes, we show that the Brauer group coincides with the cohomological Brauer group for arbitrary compact spaces. Using results from the…
Equivariant semi-topological K-homology and a theorem of Thomason
Jeremiah Heller, Jens Hornbostel
We generalize several comparison results between algebraic, semi-topological and topological K-theories to the equivariant case with respect to a finite group.
Preorientations of the derived motivic multiplicative group
Jens Hornbostel
We provide a proof in the language of model categories and symmetric spectra of Lurie's theorem that topological complex -theory represents orientations of the derived multiplic…
Schubert calculus for algebraic cobordism
Jens Hornbostel, Valentina Kiritchenko
We establish a Schubert calculus for Bott-Samelson resolutions in the algebraic cobordism ring of a complete flag variety G/B.
Tensor-triangulated categories and dualities
Baptiste Calmès, Jens Hornbostel
In a triangulated symmetric monoidal closed category, there are natural dualities induced by the internal Hom. Given a monoidal functor f^* between two such catgories and adjoint c…
Push-forwards for Witt groups of schemes
Baptiste Calmès, Jens Hornbostel
We define push-forwards for Witt groups of schemes along proper morphisms, using Grothendieck duality theory. This article is an application of results of the authors on tensor-tri…
Hermitian K-theory of the integers
A. J. Berrick, M. Karoubi
The 2-primary torsion of the higher algebraic K-theory of the integers has been computed by Rognes and Weibel. In this paper we prove analogous results for the Hermitian K-theory o…
Beta-elements and divided congruences
Jens Hornbostel, Niko Naumann
The f-invariant is an injective homomorphism from the 2-line of the Adams-Novikov spectral sequence to a group which is closely related to divided congruences of elliptic modular f…
On non-commutative twisting in etale and motivic cohomology
J. Hornbostel, G. Kings
In this paper we use ideas of the non-abelian Iwasawa main conjecture to prove a result about the first Galois cohomology of continuous Galois modules V_p(j) for large Tate-twist j…