
theorem
  for R being symmetric Relation, x being object holds Im(R,x) = Coim(R,x)
proof
  let R be symmetric Relation, x be object;
  thus Im(R,x) = R.:{x} by RELAT_1:def 16
    .= R"{x} by FRIENDS1:2
    .= Coim(R,x) by RELAT_1:def 17;
end;
