reserve a, b, k, n, m for Nat,
  i for Integer,
  r for Real,
  p for Rational,
  c for Complex,
  x for object,
  f for Function;

theorem Th35:
  frac(r) = r - scf(r).0
proof
  thus frac(r) = r - [\ rfs(r).0 /] by Def3
    .= r - scf(r).0 by Def4;
end;
