predicate fzn_seq_precede_chain_int(array[int] of var int: X) =
  if length(X) = 0 then
    true
  else
    let {
        int : l = lb_array (X) ; % least possible value
        int : u = ub_array (X) ; % greatest possible value
        int : f = min ( index_set (X ));
        array [ index_set (X) ] of var l .. u: H;
    } in
        H[f] <= 1 /\ H[f] = max (X[f], 0) /\
        forall ( i in index_set ( X) diff {f} ) (
             H[i] <= H[i-1] + 1 /\ H[i] = max (X[i], H[i-1])
        )
  endif;
