A knotted 2-dimensional foam with non-trivial cocycle invariant

Abstract

By 2-twist-spinning the knotted graph that represents the knotted handlebody $5_2$, we obtain a knotted foam in 4-dimensional space with a non-trivial quandle cocycle invariant.

14 pages and lots of very nice figures. To appear RIMS publications proceedings of the conference on Intelligence of Low Dimensional Topology 2012