let IT1, IT2 be Element of R; :: thesis: ( IT1 in X & IT1 is_maximal_wrt X, the InternalRel of R & IT2 in X & IT2 is_maximal_wrt X, the InternalRel of R implies IT1 = IT2 )
assume that
A11: IT1 in X and
A12: IT1 is_maximal_wrt X, the InternalRel of R and
A13: IT2 in X and
A14: IT2 is_maximal_wrt X, the InternalRel of R ; :: thesis: IT1 = IT2
set IR = the InternalRel of R;
A15: ( IT1 <= IT2 or IT2 <= IT1 ) by WAYBEL_0:def 29;

per cases ( [IT1,IT2] in the InternalRel of R or [IT2,IT1] in the InternalRel of R ) by A15, ORDERS_2:def 5;

suppose [IT1,IT2] in the InternalRel of R ; :: thesis: IT1 = IT2

hence IT1 = IT2 by A12, A13, WAYBEL_4:def 23; :: thesis: verum

end;

suppose [IT2,IT1] in the InternalRel of R ; :: thesis: IT1 = IT2

hence IT1 = IT2 by A11, A14, WAYBEL_4:def 23; :: thesis: verum

end;

end;