Instance Inhabitant_share : Inhabitant share := Share.bot.(* TODO: remove this, it's already in sublist.v *) 
Instance Inhabitant_mpred : Inhabitant mpred := @FF mpred Nveric.

Lemma join_shares_nth : forall shs sh1 sh i, sepalg_list.list_join sh1 shs sh -> 0 <= i < Zlength shs -> exists sh', sepalg_list.list_join (Znth i shs) (remove_Znth i shs) sh' /\ sepalg.join sh1 sh' sh.