Universiteit Leiden Mathematisch Instituut
Geometry Seminar

Wednesday, 25 April 2007, 15:45 - 16:45, room 401.

Alexei Gorinov (Nijmegen): Division theorems for the rational cohomology of discriminant complements and applications to automorphism groups.

Abstract:

Abstract: The linear group GL_n+1(C) acts in a natural way on the space of equations of smooth complete intersections of given multidegree in the complex projective space CPⁿ. We generalise a result by C. Peters and J. Steenbrink by showing that the Leray spectral sequence of the corresponding quotient map degenerates in the second term over the rationals. As a by-product of the proof, we obtain explicit expressions divisible by the order the automorphism group of any smooth projective hypersurface of given dimension and degree.