set(auto).

clear(fof_reduction).

formulas(sos).

% Andrews challenge problem

-(
   (
     (exists x all y (p(x) <-> p(y)))
     <->
     ((exists u q(u)) <-> (all v p(v)))
   )
   <->
   (
     (exists w all z (q(z) <-> q(w)))
     <->
     ((exists x1 p(x1)) <-> (all x2 q(x2)))
   )
 ).

end_of_list.