(** Some properties of [is_mill] and [dests_disjoint]. *)

Definition dests_disjoint (m1 m2: moves) : Prop :=
  list_disjoint (dests m1) (dests m2).

Lemma temp_last_pop: forall s1 d1 sigma s2 d2, temp_last ((s1, d1) :: sigma ++ (s2, d2) :: nil) -> temp_last (sigma ++ (s2, d2) :: nil).