 anti-Hopf bimodules, which are related to coefficients of Hopf cyclic cohomology and allow us to form appropriate, Yetter–Drinfeld valued, variants of extend Hilbert spaces.
Instead of considering trivial submodules, the analoga of the code spaces arise as bitensor products—a combination of cotensor and tensor products.
Our proof of their topological invariance relies on a notion of excision and uses actions of a group related to mapping class groups.
Towards computing bitensor products, we discuss ind