-val inter_list : Naive_tree.t ->Naive_tree.node list -> Naive_tree.node list -> Naive_tree.node list
-(** make a list without duplicating by using the intersection of two lists
-*)
-
-val diff_list : Naive_tree.t ->Naive_tree.node list -> Naive_tree.node list -> Naive_tree.node list
-(** difference two lists without duplicating
+val minimize_qtree : Table.query_tree -> Table.query_tree
+(** [minimize_qtree q] returns the minimum query_tree of [q]
+ [q] query_tree