Definition lset_same_support {A} (lset1 lset2 : AMap.t A) :=
  forall loc,
    AMap.find loc lset1 = None <->
    AMap.find loc lset2 = None.

Lemma lset_same_support_trans {A} (m1 m2 m3 : AMap.t A) : lset_same_support m1 m2 -> lset_same_support m2 m3 -> lset_same_support m1 m3.