+type 'a passive_clause = int * 'a clause (* weight * equation *)
+
+
+let vars_of_term ?(start_acc=[]) t =
+ let rec aux acc = function
+ | Leaf _ -> acc
+ | Var i -> if (List.mem i acc) then acc else i::acc
+ | Node l -> List.fold_left aux acc l
+ in aux start_acc t
+;;