% Mizar problem: l1_funct_4,funct_4,45,5 
fof(l1_funct_4, conjecture,  (! [A] :  (! [B] :  (! [C] :  (! [D] :  (! [E] :  (! [F] :  (! [G] :  (! [H] :  (k4_tarski(k4_tarski(A, E), k4_tarski(B, F))=k4_tarski(k4_tarski(C, G), k4_tarski(D, H)) =>  (A=C &  (B=D &  (E=G & F=H) ) ) ) ) ) ) ) ) ) ) ) ).
fof(dt_k4_tarski, axiom, $true).
fof(t1_xtuple_0, axiom,  (! [A] :  (! [B] :  (! [C] :  (! [D] :  (k4_tarski(A, B)=k4_tarski(C, D) =>  (A=C & B=D) ) ) ) ) ) ).
