Lemma 7.16.
Assuming that:
U
,
V
,
X
are independent
𝔽
2
n
-valued random variables
Then
d
[
U
|
U
+
V
;
X
]
≤
1
2
(
d
[
U
;
X
]
+
d
[
V
;
X
]
+
d
[
U
;
V
]
)
.