280 Boolean Analysis — Tensorization
280.1 Overview
Mixed power means permit a one-bit reverse inequality to extend to every cube dimension. Further noise increases every extended power mean with exponent less than one.
280.2 Declarations
Let \(s\subseteq I\) and \(t\subseteq J\) be finite sets, let \(r\ge 1\), and let \(a:I\times J\to \mathbb {R}\) satisfy \(a(i,j)\ge 0\) for \(i\in s\), \(j\in t\). Then \((\sum _{j\in t}(\sum _{i\in s}a(i,j))^r)^{1/r}\le \sum _{i\in s}(\sum _{j\in t}a(i,j)^r)^{1/r}\).
Let \(0\lt q\le p\) and \(F:\{ 0,1\} ^n\times \{ 0,1\} \to [0,\infty )\). Writing \(M_{r,z}u=(\mathbb {E}_z u^r)^{1/r}\) for uniform means, \(M_{q,x}(M_{p,b}F(x,b))\ge M_{p,b}(M_{q,x}F(x,b))\).
Let \(0\lt q\lt p\) and \(0\le \rho \le 1\). Suppose \(M_q(T_\rho u)\ge M_p(u)\) for every nonnegative function \(u\) on one bit. Then \(M_q(T_\rho f)\ge M_p(f)\) for every \(n\in \mathbb N\) and \(f:\{ 0,1\} ^n\to [0,\infty )\), where \(M_r(u)=(\mathbb {E}|u|^r)^{1/r}\). For \(d\in \mathbb N\), \(h:\{ 0,1\} ^d\to \mathbb {R}\), and \(\tau \in \mathbb {R}\), the spectral noise operator is \(T_\tau h(x)=\sum _{S\subseteq [d]}\tau ^{|S|}\widehat h(S)\chi _S(x)\), where \(\chi _S(x)=(-1)^{\sum _{i\in S}x_i}\) and \(\widehat h(S)=\mathbb {E}[h\chi _S]\) under the uniform measure.
Let \(0\lt q\lt p\lt 1\), \(0\le \rho \le 1\), and \(\rho ^2=(1-p)/(1-q)\). Every \(f:\{ 0,1\} ^n\to [0,\infty )\) satisfies \(M_q(T_\rho f)\ge M_p(f)\), where \(M_r(u)=(\mathbb {E}|u|^r)^{1/r}\) under the uniform measure. For \(d\in \mathbb N\), \(h:\{ 0,1\} ^d\to \mathbb {R}\), and \(\tau \in \mathbb {R}\), the spectral noise operator is \(T_\tau h(x)=\sum _{S\subseteq [d]}\tau ^{|S|}\widehat h(S)\chi _S(x)\), where \(\chi _S(x)=(-1)^{\sum _{i\in S}x_i}\) and \(\widehat h(S)=\mathbb {E}[h\chi _S]\) under the uniform measure.
Let \(q\lt 1\), \(0\le \rho \le \sigma \le 1\), and \(f:\{ 0,1\} ^n\to [0,\infty )\). Then \(M_q(T_\rho f)\ge M_q(T_\sigma f)\). For nonnegative functions \(u\), the extended mean is \(M_r(u)=(\mathbb {E}u^r)^{1/r}\) when \(r\gt 0\); the same formula applies for \(r\lt 0\) when \(u\) is positive everywhere. For positive \(u\), \(M_0(u)=\exp (\mathbb {E}\log u)\); if \(r\le 0\) and \(u\) has a zero, \(M_r(u)=0\). All expectations are uniform. For \(d\in \mathbb N\), \(h:\{ 0,1\} ^d\to \mathbb {R}\), and \(\tau \in \mathbb {R}\), the spectral noise operator is \(T_\tau h(x)=\sum _{S\subseteq [d]}\tau ^{|S|}\widehat h(S)\chi _S(x)\), where \(\chi _S(x)=(-1)^{\sum _{i\in S}x_i}\) and \(\widehat h(S)=\mathbb {E}[h\chi _S]\) under the uniform measure.