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K-theory, flat bundles and the Borel classes

Bjørn Jahren (1999)

Fundamenta Mathematicae

Using Hausmann and Vogel's homology sphere bundle interpretation of algebraic K-theory, we construct K-theory invariants by a theory of characteristic classes for flat bundles. It is shown that the Borel classes are detected this way, as well as the rational K-theory of integer group rings of finite groups.

K-theory of Boutet de Monvel's algebra

Severino T. Melo, Ryszard Nest, Elmar Schrohe (2003)

Banach Center Publications

We consider the norm closure 𝔄 of the algebra of all operators of order and class zero in Boutet de Monvel's calculus on a compact manifold X with boundary ∂X. Assuming that all connected components of X have nonempty boundary, we show that K₁(𝔄) ≃ K₁(C(X)) ⊕ ker χ, where χ: K₀(C₀(T*Ẋ)) → ℤ is the topological index, T*Ẋ denoting the cotangent bundle of the interior. Also K₀(𝔄) is topologically determined. In case ∂X has torsion free K-theory, we get K₀(𝔄) ≃ K₀(C(X)) ⊕ K₁(C₀(T*Ẋ)).

Le formule del grado

Simone Borghesi (2005)

Bollettino dell'Unione Matematica Italiana

Questo manoscritto è un'introduzione al concetto di formule del grado e a qualche loro applicazione. In esso si dà una formalizzazione di quello che si intenderà con formula del grado, vengono enunciati due esempi: uno cosiddetto di primo livello ed uno più generale. Successivamente si descrivono le componenti di queste formule: i numeri e gli ideali di ostruzione. Dopo un breve accenno alla dimostrazione, il testo si conclude con una sezione in cui si analizzano esplicitamente varietà algebriche...

Les motifs de Tate et les opérateurs de périodicité de Connes

Abhishek Banerjee (2014)

Annales mathématiques Blaise Pascal

Dans cet article, nous définissons une catégorie M o t ˜ C des motifs sur une catégorie monoïdale symétrique ( C , , 1 ) vérifiant certaines hypothèses. Le rôle des espaces sur ( C , , 1 ) est joué par les monoïdes (non necessairement commutatifs) dans C . Pour définir les morphismes dans M o t ˜ C , nous utilisons des classes dans les groupes d’homologie cyclique bivariante. Le but est de montrer que les opérateurs de périodicité de Connes induisent des morphismes M 𝕋 2 M dans M o t ˜ C , où 𝕋 est le motif de Tate dans M o t ˜ C .

Lie perfect, Lie central extension and generalization of nilpotency in multiplicative Lie algebras

Dev Karan Singh, Mani Shankar Pandey, Shiv Datt Kumar (2024)

Czechoslovak Mathematical Journal

This paper aims to introduce and explore the concept of Lie perfect multiplicative Lie algebras, with a particular focus on their connections to the central extension theory of multiplicative Lie algebras. The primary objective is to establish and provide proof for a range of results derived from Lie perfect multiplicative Lie algebras. Furthermore, the study extends the notion of Lie nilpotency by introducing and examining the concept of local nilpotency within multiplicative Lie algebras. The...

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