include "roots.mzn";

/** @group globals
  Returns \a s such that \a x[\p i] in \a t for all \p i in \a s
*/
function var set of int: roots(array[int] of var int: x, 
                               var set of int: t) :: promise_total =
  let { var set of index_set(x): s;
        constraint roots(x,s,t) } 
  in s;