theorem Th22:
  x,x Fr_Eq S
  proof
    reconsider s1 = 1.R as Element of R;
A1: (x`1 * x`2 - x`1 * x`2) * s1 = 0.R by VECTSP_1:19;
    s1 in S by C0SP1:def 4;
    hence thesis by A1;
  end;
