# Geometric Analysis and Topology Seminar

#### Intersection Space Cohomology and Hypersurface Singularities

**Speaker:**
Laurentiu Maxim, UW Madison

**Location:**
Warren Weaver Hall 201

**Date:**
Friday, November 18, 2011, 11 a.m.

**Synopsis:**

A recent homotopy-theoretic procedure due to Banagl assigns to a certain singular space a cell complex, its intersection space, whose rational cohomology possesses Poincare duality. This yields a new cohomology theory for singular spaces, which has a richer internal algebraic structure than intersection cohomology (e.g., it has cup products), and which addresses certain questions in type II string theory related to massless D-branes arising during a Calabi-Yau conifold transition. While intersection cohomology is stable under small resolutions, in recent joint work with Markus Banagl we proved that the new theory is often stable under smooth deformations of hypersurface singularities. When this is the case, we showed that the rational cohomology of the intersection space can be endowed with a mixed Hodge structure compatible with Deligne's mixed Hodge structure on the ordinary cohomology of the singular hypersurface.