reserve n,m for Nat;

theorem Th28:
  for f being real-valued FinSequence holds
  dom (sort_d f)=dom f & len (sort_d f)=len f
proof
  let f be real-valued FinSequence;
  f,(sort_d f) are_fiberwise_equipotent by Def5;
  hence thesis by RFINSEQ:3;
end;
