The sl(2) foam cohomology via extended TQFTs.

Authors: Carmen Caprau
Subjects: Geometric Topology
link: http://arxiv.org/abs/1001.1797
Abstract

We construct a cohomology theory for oriented links using singular cobordisms
and 2-dimensional extended Topological Quantum Field Theories (TQFTs),
categorifying the quantum sl(2) invariant. In particular, we give a description
of the universal dot-free sl(2) foam cohomology for links via a special kind of
2-dimensional extended TQFT.