An immediate consequence of the Bonami Lemma is that for any $f : \{-1,1\}^n \to {\mathbb R}$ and $k \in {\mathbb N}$, \begin{equation} \label{eqn:2-4-hypercon-k} \|\mathrm{T}_{1/\sqrt{3}} f^{=k}\|_4 = \tfrac{1}{\sqrt{3}^k} \|f^{=k}\|_4 \leq \|f^{=k}\|_2. \end{equation}

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## Recent comments

Matt Franklin: Maybe two small typos in the proof of Corollary 11.67 (p. 36...Ryan O'Donnell: I see your point, although in some sense this distinction be...Ryan O'Donnell: Thank you!Ryan O'Donnell: Yep, thanks!Ryan O'Donnell: Great catch, thanks!Matt Franklin: Maybe two small typos in last sentence before Borell's Isope...Matt Franklin: maybe small typo in Remark 11.11 (p. 328 in book): $z \tild...