## Residue forms on singular hypersurfaces

Andrzej Weber

Math. Sub. Class.: 14 F10, 14F43, 14C30
The purpose of this paper is to point out a relation between the canonical sheaf and the intersection complex of a singular algebraic variety. We focus on the hypersurface case. Let \$M\$ be a complex manifold, \$X\subset M\$ a singular hypersurface. We study residues of top-dimensional meromorphic forms with poles along \$X\$. Applying resolution of singularities sometimes we are able to construct residue classes either in \$L^2\$-cohomology of \$X\$ or in the intersection cohomology. The conditions allowing to construct these classes coincide. They can be formulated in terms of the weight filtration. Finally, provided that these conditions hold, we construct in a canonical way a lift of the residue class to cohomology of \$X\$.
Key words: Residue differential form, canonical singularities, intersection cohomology.
Contents: 1. Introduction 2. Residue as a differential form 3. Residues and resolution 4. Vanishing of hidden residues 5. Adjoint ideals 6. \$L^2\$-cohomology 7. Residues and homology 8. Hodge theory 9. Isolated singularities 10. Quasihomogeneous isolated hypersurface 11. Example: elliptic singularity