reserve a,b,c,d for Real;
reserve z,z1,z2 for Complex;

theorem Th6:
  Re(1r) = 1 & Im(1r) = 0
proof
  reconsider zz=0,j=1 as Element of REAL by XREAL_0:def 1;
  1r = [*j,zz*] by ARYTM_0:def 5;
  hence thesis by Lm2;
end;
