Definition FreelistEffect
m (L: list (Values.block * Z * Z)) (b:Values.block) (ofs:Z): bool :=
List.fold_right (fun X E b z => match X with (bb,lo,hi) =>
E b z || FreeEffect m lo hi bb b z
end)
EmptyEffect L b ofs.

Lemma FreelistEffect_validblock: forall l m b ofs
(EFF: FreelistEffect m l b ofs = true),
Mem.valid_block m b.