Corrado de Concini

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0 Introduction In this paper we describe, for any given nite family of sub-spaces of a vector space or for linear subspaces in aane or projective space, a smooth model, proper over the given space, in which the complement of these subspaces is unchanged but the family of subspaces is replaced by a divisor with normal crossings. This model can be described(More)
In [8] de Concini, Kac and Procesi introduced the simply connected quantised universal enveloping algebra U = Uε,P (g) over C at a primitive lth root of unity ε associated to a simple finite-dimensional complex Lie algebra g. The importance of the study of the centre Z of U and its spectrum Maxspec(Z) is pointed out in [7,8]. In this article we consider the(More)
Let F be a field and Gr(i, F ) be the Grassmannian of idimensional linear subspaces of F . A map f : Gr(i, F ) −→ Gr(j, F ) is called nesting if l ⊂ f(l) for every l ∈ Gr(i, F ). Glover, Homer and Stong showed that there are no continuous nesting maps Gr(i, C) −→ Gr(j, C) except for a few obvious ones. We prove a similar result for algebraic nesting maps(More)