00100 E( F(F(X1 X2 X3) X4 F(X1 X2 X5))F(X1 X2 F(X3 X4 X5))); 00200 E(F(X2 X1 X1) X1); 00300 E(F(X1 X2 I(X2)) X2); 00400 ; 00500 ; 00600 ∀(X1 X2)E(F(I(X2)X2 X1) X1); ; 00700