Theorem 14 says that if $f$ is an unbiased linear threshold function $f(x) = \mathrm{sgn}(a_1 x_1 + \cdots + a_n x_n)$ in which all $a_i$’s are “small” then the noise stability $\mathbf{Stab}_\rho[f]$ is at least (roughly) $\frac{2}{\pi} \arcsin \rho$. Rephrasing in terms of noise sensitivity, this means $\mathbf{NS}_\delta[f]$ is at most (roughly) $\tfrac{2}{\pi} \sqrt{\delta} [...]

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Ryan O'Donnell: Thanks! It's corrected in the book.Ohad Klein: In theorem 44, I think the written taylor expansion is the o...Ryan O'Donnell: Yes, thanks!Noam Lifshitz: In exercise 15 (Ex 18 in the book) is it true that $V_j=T_j$...Ryan O'Donnell: Thanks!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...