Gowers-Cauchy-Schwarz inequality
= Gowers-Cauchy-Schwarz inequality
{c}
Repeated <Cauchy-Schwarz inequality> gives
$$
\left|\left\langle(f_\epsilon)\right\rangle_{U^k}\right|
\leq\prod_{\epsilon\in\{0,1\}^k}\|f_\epsilon\|_{U^k}.
$$
= Gowers-Cauchy-Schwarz inequality
{c}
Repeated <Cauchy-Schwarz inequality> gives
$$
\left|\left\langle(f_\epsilon)\right\rangle_{U^k}\right|
\leq\prod_{\epsilon\in\{0,1\}^k}\|f_\epsilon\|_{U^k}.
$$