 reserve S for satisfying_Tarski-model TarskiGeometryStruct;
 reserve a, b, c, d, e, f, o, p, q, r, s,
    v, w, u, x, y, z, a9, b9, c9, d9, x9, y9, z for POINT of S;

theorem EquivReflexive:
  a,b equiv a,b
  proof
    b,a equiv a,b by A1;
    hence thesis by A2;
  end;
