* Marius Vollmer <marius.vollmer@gmail.com> [2009-03-29 15:02]: > You just need to do the expansion one more time: > > (A, B) | (C, D) > -> A | (C D), B | (C D) > -> A | C, A | D, B | C, B | D > > Every expression involving AND / OR can be written in a 'two-level' form > > (A or B or ...) and (X or Y or ..) and ... Right. Thanks, -- Rafael