229 Boolean Analysis — Gaussian Density
229.1 Overview
Translated Gaussian densities represent affine Gaussian indicator averages and admit integrable bounds for their first two mean derivatives. These estimates give differentiability, global derivative bounds, and Lipschitz regularity of bounded measurable Gaussian averages.
229.2 Declarations
Let \(A\subseteq \mathbb R\) be measurable, \(c,s\in \mathbb R\), and \(s\ne 0\). For \(Z\sim N(0,1)\) and the Gaussian density \(p_{s^2}(c,z)\) with mean \(c\) and variance \(s^2\), \(\mathbb E1_A(c+sZ)=\int _{\mathbb R}p_{s^2}(c,z)1_A(z)\, dz\).
For \(v\ge 0\), put \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\) when \(v\gt 0\), and \(p_0(c,z)=0\); take division by zero to be zero. For all real \(c,z\), the derivative at \(c\) of \(m\mapsto p_v(m,z)\) is \(((z-c)/v)p_v(c,z)\).
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). For every \(M\ge 0\), there exists a Lebesgue-integrable \(b:\mathbb R\to \mathbb R\) such that \(|((z-m)/v)p_v(m,z)|\le b(z)\) for all \(z\in \mathbb R\) and all \(m\) with \(|m|\le M\).
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). Let \(f:\mathbb R\to \mathbb R\) be measurable with \(|f(z)|\le 1\) for all \(z\). For every \(c\in \mathbb R\), the derivative at \(c\) of \(m\mapsto \int p_v(m,z)f(z)\, dz\) is \(\int ((z-c)/v)p_v(c,z)f(z)\, dz\).
For \(v\ge 0\), put \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\) when \(v\gt 0\), and \(p_0(c,z)=0\); take division by zero to be zero. For real \(c,z\), the derivative at \(c\) of \(m\mapsto ((z-m)/v)p_v(m,z)\) is \(((z-c)^2/v^2-1/v)p_v(c,z)\).
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). For every \(M\ge 0\), there is a Lebesgue-integrable \(b:\mathbb R\to \mathbb R\) such that \(|((z-m)^2/v^2-1/v)p_v(m,z)|\le b(z)\) for all real \(z\) and all \(m\) with \(|m|\le M\).
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). If \(f:\mathbb R\to \mathbb R\) is measurable and \(|f|\le 1\), then for each real \(c\) the derivative at \(c\) of \(m\mapsto \int ((z-m)/v)p_v(m,z)f(z)\, dz\) is \(\int ((z-c)^2/v^2-1/v)p_v(c,z)f(z)\, dz\).
For every \(c\in \mathbb R\) and \(v\ge 0\), a random variable \(Z\sim N(c,v)\) satisfies \(\mathbb E(Z-c)^2=v\), including the point-mass law when \(v=0\).
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). Let \(c\in \mathbb R\) and \(g,b:\mathbb R\to \mathbb R\). If \(b\) is integrable for \(N(c,v)\) and \(|g(z)|\le b(z)\) for every \(z\), then \(|\int p_v(c,z)g(z)\, dz|\le \int b(z)\, dN(c,v)(z)\), with a nonintegrable integral on the left assigned value zero.
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). For any function \(f:\mathbb R\to \mathbb R\) with \(|f|\le 1\) and any real \(c\), \(|\int ((z-c)^2/v^2-1/v)p_v(c,z)f(z)\, dz|\le 2/v\), where nonintegrable integrals are assigned zero.
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). For any function \(f:\mathbb R\to \mathbb R\) with \(|f|\le 1\) and any real \(c\), \(|\int ((z-c)/v)p_v(c,z)f(z)\, dz|\le 1+1/v\), where nonintegrable integrals are assigned zero.
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). For measurable \(f:\mathbb R\to \mathbb R\) with \(|f|\le 1\), the function \(c\mapsto \int ((z-c)/v)p_v(c,z)f(z)\, dz\) is globally \(2/v\)-Lipschitz.
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). For measurable \(f:\mathbb R\to \mathbb R\) with \(|f|\le 1\), the function \(c\mapsto \int p_v(c,z)f(z)\, dz\) is globally \((1+1/v)\)-Lipschitz.
Let \(v\gt 0\) and \(p_v(c,z)=(2\pi v)^{-1/2}\exp (-(z-c)^2/(2v))\). For measurable \(f:\mathbb R\to \mathbb R\) with \(|f|\le 1\), the function \(c\mapsto \int p_v(c,z)f(z)\, dz\) is continuously differentiable on \(\mathbb R\).