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Algebraic characteristic classes for idempotent matrices.

Francisco Gómez (1992)

Publicacions Matemàtiques

This paper contains the algebraic analog for idempotent matrices of the Chern-Weil theory of characteristic classes. This is used to show, algebraically, that the canonical line bundle on the complex projective space is not stably trivial. Also a theorem is proved saying that for any smooth manifold there is a canonical epimorphism from the even dimensional algebraic de Rham cohomology of its algebra of smooth functions onto the standard even dimensional de Rham cohomology of the manifold.

Algebroid nature of the characteristic classes of flat bundles

Jan Kubarski (1998)

Banach Center Publications

The following two homotopic notions are important in many domains of differential geometry: - homotopic homomorphisms between principal bundles (and between other objects), - homotopic subbundles. They play a role, for example, in many fundamental problems of characteristic classes. It turns out that both these notions can be - in a natural way - expressed in the language of Lie algebroids. Moreover, the characteristic homomorphisms of principal bundles (the Chern-Weil homomorphism [K4], or the...

Chern classes of vector bundles with singular connections

Guiseppe De Cecco (1982)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Si fa vedere che alcune classi di Chern di fibrati vettoriali complessi possono essere costruite non solo partendo da connessioni C ma, sotto certe condizioni, anche da connessioni lineari singolari. Nel caso particolare del fibrato tangente possono essere costruite anche a partire da metriche singolari. Viene fatto uso in modo essenziale della L 2 -coomologia di de Rham (introdotta da Cheeger e Teleman).

Classes caractéristiques exotiques et -connexité des espaces de connexions

Daniel Lehmann (1974)

Annales de l'institut Fourier

Le but de ce travail est double : d’une part, généraliser la construction des classes exotiques pour l’appliquer à d’autres problèmes géométriques que ceux issus des Γ -structures ; d’autre part, préciser, grâce à la notion de J -connexité, remplaçant avantageusement les formules de dérivation utilisées précédemment, l’argument d’invariance homotopique permettant d’obtenir des théorèmes de rigidité, montrant simultanément pourquoi la seule connexité des ensembles de connexions considérés ne suffit...

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