“…turns out to be very difficult. Probably the most conclusing argument comes from the group case where the description and classification of all bicrossed products between two finite cyclic groups is still an open question (see [4] for an up-to-date account on the subject). Nevertheless, this topic has been intensively studied in several papers including [1], [3], [7], [8], [9], [14], [22], to mention only a few, and it turned out to be an effective method of constructing new objects (groups, associative algebras, Hopf algebras etc.)…”