reserve x for object;
reserve D for set;
reserve p for PartialPredicate of D;
reserve D for non empty set;
reserve p,q,r for PartialPredicate of D;

theorem
  PP_imp(PP_False(D),p) = PP_True(D)
  proof
    PP_not(PP_False(D)) = PP_True(D) by Th43;
    hence thesis by Th45;
  end;
