Definition isVAL (r : resource) :=
match r with
| YES _ _ (VAL _) _ => Logic.True
| _ => False
end.

Lemma pures_same_necR phi1 phi2 phi1' :
level phi1 = level phi2 ->
pures_same phi1 phi2 ->
necR phi1 phi1' ->
exists phi2',
level phi1' = level phi2' /\
pures_same phi1' phi2' /\
necR phi2 phi2'.