Lemma 4.10
(GowersβCauchyβSchwarz Inequality)
.
Assuming that:
f
π
:
G
β
β
,
π
β
{
0
,
1
}
3
Then
|
β¨
(
f
π
)
π
β
{
0
,
1
}
3
β©
U
3
(
G
)
β€
β
π
β
{
0
,
1
}
3
β₯
f
π
β₯
U
3
(
G
)
.