Krzysztof Putyra, University of Zurich, An equivalence between gl(2)-foams and Bar-Natan cobordisms
The original construction of the Khovanov homology of a link can be seen as a formal complex in the category of flat tangles and surfaces between them. There is a way to associate a chain map with a link cobordism, but only up to a sign. Blanchet has fixed this by introducing the category of gl(2)-foams, certain singular cobordisms…