theorem Th86:
  for A being 0-based finite non empty array of O
  ex B being permutation of A st B is ascending
  proof
    let A be 0-based finite non empty array of O;
    consider C being 0-based arr_computation of A such that
A1: C is complete by Th85;
    C is finite by Th76; then
    reconsider B = last C as permutation of A by Th78;
    take B;
    thus B is ascending by A1;
  end;
