match v1,v2 with
[],_
| _,[] -> false
- | s1::tl1, s2::_ when s1 < s2 -> sub_ex tl1 v2
- | s1::_, s2::tl2 when s2 < s1 -> false
- | s1::_, s2::_ when s1 = s2 -> true
+ | s1::tl1, s2::_ when s1 < s2 -> meet_ex tl1 v2
+ | s1::_, s2::tl2 when s2 < s1 -> meet_ex v1 tl2
+ | _, _ -> true
;;