reserve R for Ring,
  I for Ideal of R,
  a, b for Element of R;
reserve R for add-associative right_zeroed right_complementable Abelian
    distributive left_unital non empty doubleLoopStr;
reserve I for Ideal of R;
reserve a,b for Element of R;
reserve x, y for Element of R/I;

theorem Th12:
  Class(EqRel(R,I),a) is Element of R/I
proof
  the carrier of R/I = Class EqRel(R,I) by Def6;
  hence thesis by EQREL_1:def 3;
end;
