% Mizar problem: t53_enumset1,enumset1,305,57 
fof(t53_enumset1,conjecture,(
    ! [A,B,C,D,E,F] : k4_enumset1(A,B,C,D,E,F) = k2_xboole_0(k1_enumset1(A,B,C),k1_enumset1(D,E,F)) ),
    inference(mizar_bg_added,[status(thm)],[commutativity_k2_xboole_0,idempotence_k2_xboole_0,dt_k1_enumset1,dt_k2_xboole_0,dt_k4_enumset1,l60_enumset1]),
    [file(enumset1,t53_enumset1)]).

fof(commutativity_k2_xboole_0,axiom,(
    ! [A,B] : k2_xboole_0(A,B) = k2_xboole_0(B,A) ),
    file(xboole_0,k2_xboole_0),
    []).

fof(idempotence_k2_xboole_0,axiom,(
    ! [A,B] : k2_xboole_0(A,A) = A ),
    file(xboole_0,k2_xboole_0),
    []).

fof(dt_k1_enumset1,axiom,(
    $true ),
    file(enumset1,k1_enumset1),
    []).

fof(dt_k2_xboole_0,axiom,(
    $true ),
    file(xboole_0,k2_xboole_0),
    []).

fof(dt_k4_enumset1,axiom,(
    $true ),
    file(enumset1,k4_enumset1),
    []).

fof(l60_enumset1,axiom,(
    ! [A,B,C,D,E,F] : k4_enumset1(A,B,C,D,E,F) = k2_xboole_0(k1_enumset1(A,B,C),k1_enumset1(D,E,F)) ),
    file(enumset1,l60_enumset1),
    []).