% Mizar problem: t104_xboole_1,xboole_1,1233,56 
fof(t104_xboole_1,conjecture,(
    ! [A,B] : 
      ( ~ ( ~ r2_xboole_0(A,B)
          & A != B
          & ~ r2_xboole_0(B,A) )
    <=> r3_xboole_0(A,B) ) ),
    inference(mizar_bg_added,[status(thm)],[antisymmetry_r2_xboole_0,d8_xboole_0,d9_xboole_0,irreflexivity_r2_xboole_0,reflexivity_r1_tarski,reflexivity_r3_xboole_0,symmetry_r3_xboole_0]),
    [file(xboole_1,t104_xboole_1)]).

fof(antisymmetry_r2_xboole_0,axiom,(
    ! [A,B] : 
      ( r2_xboole_0(A,B)
     => ~ r2_xboole_0(B,A) ) ),
    file(xboole_0,r2_xboole_0),
    []).

fof(d8_xboole_0,axiom,(
    ! [A,B] : 
      ( r2_xboole_0(A,B)
    <=> ( r1_tarski(A,B)
        & A != B ) ) ),
    file(xboole_0,d8_xboole_0),
    []).

fof(d9_xboole_0,axiom,(
    ! [A,B] : 
      ( r3_xboole_0(A,B)
    <=> ( r1_tarski(A,B)
        | r1_tarski(B,A) ) ) ),
    file(xboole_0,d9_xboole_0),
    []).

fof(irreflexivity_r2_xboole_0,axiom,(
    ! [A,B] : ~ r2_xboole_0(A,A) ),
    file(xboole_0,r2_xboole_0),
    []).

fof(reflexivity_r1_tarski,axiom,(
    ! [A,B] : r1_tarski(A,A) ),
    file(tarski,r1_tarski),
    []).

fof(reflexivity_r3_xboole_0,axiom,(
    ! [A,B] : r3_xboole_0(A,A) ),
    file(xboole_0,r3_xboole_0),
    []).

fof(symmetry_r3_xboole_0,axiom,(
    ! [A,B] : 
      ( r3_xboole_0(A,B)
     => r3_xboole_0(B,A) ) ),
    file(xboole_0,r3_xboole_0),
    []).