3 papers
math.QA2005
Quantum principal bundles up to homotopy equivalence
Christian Kassel
We translate some fundamental properties satisfied by topological principal bundles into the setting of Hopf-Galois extensions. The properties are: functoriality, homotopy, and tri…
math.RA2000
Explicit elements of norm one for cyclic groups
Eli Aljadeff, Christian Kassel
Let G be a cyclic p-group of order p^n acting by automorphisms on a (non-necessarily commutative) ring R. Suppose there is an element x in R such that (1 + t + ... + t^{p-1})(x) =…
math.QA1999
The Hall algebra of the category of coherent sheaves on the projective line
Pierre Baumann, Christian Kassel
To an abelian category A of homological dimension 1 satisfying certain finiteness conditions, one can associate an algebra, called the Hall algebra. Kapranov studied this algebra w…