let rec set_union v1 v2 =
match v1, v2 with
| [], v -> v
- | v, [] -> v (* (zz h1 ">" h2); *)
+ | v, [] -> v
| h1 :: t1, h2 :: t2 when h1 < h2 -> h1 :: set_union t1 v2
| h1 :: t1, h2 :: t2 when h1 > h2 -> h2 :: set_union v1 t2
| h1 :: t1, _ :: t2 -> h1 :: set_union t1 t2
+let rec set_intersect v1 v2 =
+ match v1, v2 with
+ | [], v -> []
+ | v, [] -> []
+ | h1 :: t1, h2 :: _ when h1 < h2 -> set_intersect t1 v2
+ | h1 :: _, h2 :: t2 when h1 > h2 -> set_intersect v1 t2
+ | h1 :: t1, _ :: t2 -> h1 :: set_intersect t1 t2
+
let rec iter f = function
| [] -> []
| head :: tail -> set_union (f head) (iter f tail)
let rec mql_iter2 f l1 l2 = match l1, l2 with
| [], [] -> []
| h1 :: t1, h2 :: t2 -> mql_union (f h1 h2) (mql_iter2 f t1 t2)
- | _ -> raise (Invalid_argument "mql_itwr2")
+ | _ -> raise (Invalid_argument "mql_iter2")
let rec mql_prod g1 g2 =
let mql_prod_aux a = iter (fun h -> [mql_union a h]) g2 in
| (r1, _) :: t1, (r2, _) :: _ when r1 < r2 -> mql_intersect t1 s2
| (r1, _) :: _, (r2, _) :: t2 when r1 > r2 -> mql_intersect s1 t2
| (r1, g1) :: t1, (_, g2) :: t2 ->
- (r1, mql_prod g1 g2) :: mql_intersect t1 t2
+ (r1, set_intersect g1 g2) :: mql_intersect t1 t2
let rec mql_diff s1 s2 =
match s1, s2 with