Return to Colloquia & Seminar listing

### Whitehead Torsion for Floer Homology

**Geometry/Topology**

Speaker: | Michael Sullivan, Stanford University |

Location: | 693 Kerr |

Start time: | Wed, Jan 6 1999, 4:10PM |

Floer homology has become a popular field of study in symplectic geometry, with applications to topics like Lagrangian intersection theory and the Arnold Conjecture. In this lecture I construct two K-theoretic invariants for the chain complexes of Floer homology. First I briefly review the Floer homology theory of two intersecting Lagrangian submanifolds. Then I review algebraic definitions of Whitehead torsion and the second Whitehead group. I show how these algebraic structures can define invariants for a Floer chain complex or one-parameter family of complexes when the Floer homology vanishes. Finally, I sketch a proof which uses 'gluing' theorems and other Floer homology analysis to show that these invariants are independent of almost-complex structures and exact symplectomorphisms.