Double Spaces with Isolated Singularities
نویسنده
چکیده
We prove the non-rationality of a double cover of P branched over a hypersurface F ⊂ P of degree 2n having isolated singularities such that n ≥ 4 and every singular points of the hypersurface F is ordinary, i.e. the projectivization of its tangent cone is smooth, whose multiplicity does not exceed 2(n− 2).
منابع مشابه
L-cohomology of Spaces with Non-isolated Conical Singularities and Non-multiplicativity of the Signature
We study from a mostly topological standpoint, the L-signature of certain spaces with non-isolated conical singularities. The contribution from the singularities is identified with a topological invariant of the link fibration of the singularities. This invariant measures the failure of the signature to behave multiplicatively for fibrations for which the boundary of the fibre in nonempty. The ...
متن کاملIntersection Spaces and Hypersurface Singularities
We give an elementary introduction to the first author’s theory of intersection spaces associated to complex projective varieties with only isolated singularities. We also survey recent results on the deformation invariance of intersection space homology in the context of projective hypersurfaces with an isolated singularity.
متن کاملToric Symplectic Singular Spaces I: Isolated Singularities
We generalize a theorem of Delzant classifying compact connected symplectic manifolds with completely integrable torus actions to certain singular symplectic spaces. The assumption on singularities is that if they are not finite quotient then they are isolated.
متن کاملFace numbers of pseudomanifolds with isolated singularities
We investigate the face numbers of simplicial complexes with Buchsbaum vertex links, especially pseudomanifolds with isolated singularities. This includes deriving Dehn-Sommerville relations for pseudomanifolds with isolated singularities and establishing lower and upper bound theorems when the singularities are also homologically isolated. We give formulas for the Hilbert function of a generic...
متن کاملRings of Singularities
This paper is a slightly revised version of an introduction into singularity theory corresponding to a series of lectures given at the ``Advanced School and Conference on homological and geometrical methods in representation theory'' at the International Centre for Theoretical Physics (ICTP), Miramare - Trieste, Italy, 11-29 January 2010. We show how to associate to a triple of posit...
متن کامل