Factorization of conditional expectations on Kac algebras and quantum double coset hypergroups. (English) Zbl 1097.46047
Ukr. Mat. Zh. 55, No. 12, 1669-1677 (2003) and Ukr. Math. J. 55, No. 12, 1994-2005 (2003).
Reviewer: Anatoly N. Kochubei (Kyïv)