Definition vis mu := fun b => locBlocksSrc mu b || frgnBlocksSrc mu b.Definition visTgt mu := fun b => locBlocksTgt mu b || frgnBlocksTgt mu b.Inductive reach (m:mem) (B:block -> Prop): list (block * Z) -> block -> Prop :=
  reach_nil: forall b, B b -> reach m B nil b
| reach_cons: forall b L b' z off n q,
                     reach m B L b' ->
                     Mem.perm m b' z Cur Readable ->
                     ZMap.get z (PMap.get b' (Mem.mem_contents m)) =
                     Fragment (Vptr b off) q n ->
              reach m B ((b',z)::L) b.Inductive reach (m:mem) (B:block -> Prop): list (block * Z) -> block -> Prop :=
  reach_nil: forall b, B b -> reach m B nil b
| reach_cons: forall b L b' z off n q,
                     reach m B L b' ->
                     Mem.perm m b' z Cur Readable ->
                     ZMap.get z (PMap.get b' (Mem.mem_contents m)) =
                     Fragment (Vptr b off) q n ->
              reach m B ((b',z)::L) b.Inductive reach (m:mem) (B:block -> Prop): list (block * Z) -> block -> Prop :=
  reach_nil: forall b, B b -> reach m B nil b
| reach_cons: forall b L b' z off n q,
                     reach m B L b' ->
                     Mem.perm m b' z Cur Readable ->
                     ZMap.get z (PMap.get b' (Mem.mem_contents m)) =
                     Fragment (Vptr b off) q n ->
              reach m B ((b',z)::L) b.Fixpoint reach' (m:mem) (B:block -> Prop) (L:list (block * Z)): block -> Prop:=
  match L with
    nil => B
  | l::L => match l with
             (b',z) => match ZMap.get z (PMap.get b' (Mem.mem_contents m))
                       with Fragment (Vptr b off) q  n => fun bb => bb = b /\
                                               Mem.perm m b' z Cur Readable /\
                                               reach' m B L b'
                           | _ => fun bb => False
                       end
            end
  end.

Lemma reach_reach': forall m B L b1, reach m B L b1 <-> reach' m B L b1.