% Mizar problem: t19_enumset1,enumset1,435,63 
fof(t19_enumset1, conjecture,  (! [A] :  (! [B] :  (! [C] :  (! [D] :  (! [E] :  (! [F] :  (! [G] : k5_enumset1(A, B, C, D, E, F, G)=k2_xboole_0(k2_enumset1(A, B, C, D), k1_enumset1(E, F, G))) ) ) ) ) ) ) ).
fof(commutativity_k2_xboole_0, axiom,  (! [A, B] : k2_xboole_0(A, B)=k2_xboole_0(B, A)) ).
fof(idempotence_k2_xboole_0, axiom,  (! [A, B] : k2_xboole_0(A, A)=A) ).
fof(dt_k1_enumset1, axiom, $true).
fof(dt_k2_enumset1, axiom, $true).
fof(dt_k2_xboole_0, axiom, $true).
fof(dt_k5_enumset1, axiom, $true).
fof(l28_enumset1, axiom,  (! [A] :  (! [B] :  (! [C] :  (! [D] :  (! [E] :  (! [F] :  (! [G] : k5_enumset1(A, B, C, D, E, F, G)=k2_xboole_0(k2_enumset1(A, B, C, D), k1_enumset1(E, F, G))) ) ) ) ) ) ) ).
