reserve i, j, m, n for Nat,
  z, B0 for set,
  f, x0 for real-valued FinSequence;

theorem
  <* 1 *> is Permutation of {1}
proof
  set g=<* 1 *>;
A1: rng g={1} by FINSEQ_1:38;
  dom g={1} by FINSEQ_1:2,38;
  then reconsider f=g as Function of {1},{1} by A1,FUNCT_2:1;
  f is one-to-one onto Function of {1},{1} by A1,FUNCT_2:def 3;
  hence thesis;
end;
