Lebesgue classes and preparation of real constructible functions

TL;DR

This paper develops a detailed structure theorem for constructible functions and measures, linking their $L^p$-integrability properties with geometric and analytic aspects of globally subanalytic functions.

Contribution

It introduces a new structure theorem describing the $L^p$-space membership of constructible functions with respect to parametrized measures, connecting analysis and geometry.

Findings

Characterization of the set where functions are in $L^p$ spaces

A preparation theorem for constructible functions and measures

Bridging analysis of $L^p$ spaces with geometric zero loci

Abstract

We call a function constructible if it has a globally subanalytic domain and can be expressed as a sum of products of globally subanalytic functions and logarithms of positively-valued globally subanalytic functions. For any $q > 0$ and constructible functions $f$ and $\mu$ on $E\times\RR^n$, we prove a theorem describing the structure of the set of all $(x,p)$ in $E \times (0,\infty]$ for which $y \mapsto f(x,y)$ is in $L^p(|\mu|_{x}^{q})$, where $|\mu|_{x}^{q}$ is the positive measure on $\RR^n$ whose Radon-Nikodym derivative with respect to the Lebesgue measure is $y\mapsto |\mu(x,y)|^q$. We also prove a closely related preparation theorem for $f$ and $\mu$. These results relate analysis (the study of $L^p$-spaces) with geometry (the study of zero loci).