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Dualization in algebraic K-theory and the invariant e¹ of quadratic forms over schemes

Marek Szyjewski (2011)

Fundamenta Mathematicae

In the classical Witt theory over a field F, the study of quadratic forms begins with two simple invariants: the dimension of a form modulo 2, called the dimension index and denoted e⁰: W(F) → ℤ/2, and the discriminant e¹ with values in k₁(F) = F*/F*², which behaves well on the fundamental ideal I(F)= ker(e⁰). Here a more sophisticated situation is considered, of quadratic forms over a scheme and, more generally, over an exact category with duality. Our purposes are: ...

Effective chain complexes for twisted products

Marek Filakovský (2012)

Archivum Mathematicum

In the paper weak sufficient conditions for the reduction of the chain complex of a twisted cartesian product F × τ B to a chain complex of free finitely generated abelian groups are found.

Espaces homogènes et arithmétique des schémas en groupes réductifs sur les anneaux de Dedekind

Jean-Claude Douai (1995)

Journal de théorie des nombres de Bordeaux

Soit S un schéma arithmétique de dimension 1 , c’est-à-dire le spectre de l’anneau des entiers d’un corps de nombres ou une courbe algébrique, lisse, irréductible, définie sur un corps fini ou algébriquement clos. Nous associons à un S -espace homogène (à gauche) X d’un groupe réductif G dont l’isotropie est aussi un groupe réductif H une classe caractéristique qui, dans le cas où H est semi-simple, vit dans un H 3 de S à valeurs dans le noyau du revêtement universel d’une S -forme de H . Cette classe...

Examples of homotopy Lie algebras

Klaus Bering, Tom Lada (2009)

Archivum Mathematicum

We look at two examples of homotopy Lie algebras (also known as L algebras) in detail from two points of view. We will exhibit the algebraic point of view in which the generalized Jacobi expressions are verified by using degree arguments and combinatorics. A second approach using the nilpotency of Grassmann-odd differential operators Δ to verify the homotopy Lie data is shown to produce the same results.

Excision in entire cyclic cohomology

Ralf Meyer (2001)

Journal of the European Mathematical Society

We prove that entire and periodic cyclic cohomology satisfy excision for extensions of bornological algebras with a bounded linear section. That is, for such an extension we obtain a six term exact sequence in cohomology.

Existence of Gorenstein projective resolutions and Tate cohomology

Peter Jørgensen (2007)

Journal of the European Mathematical Society

Existence of proper Gorenstein projective resolutions and Tate cohomology is proved over rings with a dualizing complex. The proofs are based on Bousfield Localization which is originally a method from algebraic topology.

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