theorem Th12:
  R is_reflexive_in [:A,A:] implies id A is_FormalIz_of R
proof
  assume
A1: for x being object st x in [:A,A:] holds [x,x] in R;
  let x,y;
A2: [x,y] in [:A,A:] by ZFMISC_1:def 2;
  thus thesis by A1,A2;
end;
