User Portlet User Portlet

Discussions
I gave up trying to determine the partial sets' complements so that the outcome would be {{P2,P3,P4},{P1,P4}} In[193]:= TT := {{{P1}, {P2, P3}}} XX := {P1, P2, P3, P4} In[195]:= MapThread[Complement, {{Flatten[XX]}, {Flatten[TT]}},...