% Mizar problem: t21_gate_1,gate_1,430,32 
fof(t21_gate_1, conjecture,  (! [A] :  (! [B] :  (! [C] :  (! [D] :  ( ~ ( ( ~ (v1_xboole_0(k15_gate_1(A, B, C, D)))  &  (v1_xboole_0(A) &  (v1_xboole_0(B) &  (v1_xboole_0(C) & v1_xboole_0(D)) ) ) ) )  &  ~ ( ( ~ ( (v1_xboole_0(A) &  (v1_xboole_0(B) &  (v1_xboole_0(C) & v1_xboole_0(D)) ) ) )  & v1_xboole_0(k15_gate_1(A, B, C, D))) ) ) ) ) ) ) ).
fof(dt_k15_gate_1, axiom, $true).
fof(dt_k1_gate_1, axiom, $true).
fof(dt_k1_xboole_0, axiom, $true).
fof(fc1_gate_1, axiom,  (! [A] :  (v1_xboole_0(A) =>  ~ (v1_xboole_0(k1_gate_1(A))) ) ) ).
fof(fc1_xboole_0, axiom, v1_xboole_0(k1_xboole_0)).
fof(fc2_gate_1, axiom,  (! [A] :  ( ~ (v1_xboole_0(A))  => v1_xboole_0(k1_gate_1(A))) ) ).
fof(rc1_xboole_0, axiom,  (? [A] : v1_xboole_0(A)) ).
fof(rc2_xboole_0, axiom,  (? [A] :  ~ (v1_xboole_0(A)) ) ).
fof(d15_gate_1, axiom,  (! [A] :  (! [B] :  (! [C] :  (! [D] :  ( ( ~ ( (v1_xboole_0(A) &  (v1_xboole_0(B) &  (v1_xboole_0(C) & v1_xboole_0(D)) ) ) )  => k15_gate_1(A, B, C, D)=k1_gate_1(k1_xboole_0))  &  ~ ( (v1_xboole_0(A) &  (v1_xboole_0(B) &  (v1_xboole_0(C) &  (v1_xboole_0(D) &  ~ (k15_gate_1(A, B, C, D)=k1_xboole_0) ) ) ) ) ) ) ) ) ) ) ).
