Duality and Pro-Spectra.
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: ...
In the paper weak sufficient conditions for the reduction of the chain complex of a twisted cartesian product to a chain complex of free finitely generated abelian groups are found.
Soit un schéma arithmétique de dimension , 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 -espace homogène (à gauche) d’un groupe réductif dont l’isotropie est aussi un groupe réductif une classe caractéristique qui, dans le cas où est semi-simple, vit dans un de à valeurs dans le noyau du revêtement universel d’une -forme de . Cette classe...
We look at two examples of homotopy Lie algebras (also known as 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 to verify the homotopy Lie data is shown to produce the same results.
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 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.