% Mizar problem: t5_xboole_0,xboole_0,260,48 
fof(t5_xboole_0,conjecture,(
    ! [A,B,C] : ~ ( r1_xboole_0(A,B)
      & r2_hidden(C,k2_xboole_0(A,B))
      & ~ ( r2_hidden(C,A)
          & ~ r2_hidden(C,B) )
      & ~ ( r2_hidden(C,B)
          & ~ r2_hidden(C,A) ) ) ),
    inference(mizar_bg_added,[status(thm)],[commutativity_k2_xboole_0,idempotence_k2_xboole_0,symmetry_r1_xboole_0,antisymmetry_r2_hidden,dt_k2_xboole_0,d2_xboole_0,t3_xboole_0]),
    [file(xboole_0,t5_xboole_0)]).

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(symmetry_r1_xboole_0,axiom,(
    ! [A,B] : 
      ( r1_xboole_0(A,B)
     => r1_xboole_0(B,A) ) ),
    file(xboole_0,r1_xboole_0),
    []).

fof(antisymmetry_r2_hidden,axiom,(
    ! [A,B] : 
      ( r2_hidden(A,B)
     => ~ r2_hidden(B,A) ) ),
    file(hidden,r2_hidden),
    []).

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

fof(d2_xboole_0,axiom,(
    ! [A,B,C] : 
      ( C = k2_xboole_0(A,B)
    <=> ! [D] : 
          ( r2_hidden(D,C)
        <=> ( r2_hidden(D,A)
            | r2_hidden(D,B) ) ) ) ),
    file(xboole_0,d2_xboole_0),
    []).

fof(t3_xboole_0,axiom,(
    ! [A,B] : 
      ( ~ ( ~ r1_xboole_0(A,B)
          & ! [C] : ~ ( r2_hidden(C,A)
              & r2_hidden(C,B) ) )
      & ~ ( ? [C] : 
              ( r2_hidden(C,A)
              & r2_hidden(C,B) )
          & r1_xboole_0(A,B) ) ) ),
    file(xboole_0,t3_xboole_0),
    []).