Parameter REACH : mem -> (block -> bool) -> block -> bool.

Lemma REACH_inject: forall m1 m2 j (J: Mem.inject j m1 m2) B1 B2
(HB: forall b, B1 b = true -> exists jb d, j b = Some(jb,d) /\ B2 jb = true)
b1 (R: REACH m1 B1 b1 = true),
exists b2 d, j b1 = Some(b2,d) /\ REACH m2 B2 b2 = true.