Stability of the $L^{p}$-Poincaré inequality for the Lebesgue and Gaussian probability measures with explicit geometric dependency
Nurgissa Yessirkegenov, Amir Zhangirbayev
TL;DR
This paper proves stability for the $L^{p}$-Poincaré inequality under both Lebesgue and Gaussian measures by linking the deficit to the $L^{p}$-distance to the optimizer manifold $E_{Poin}$. The authors derive explicit, geometry-dependent lower bounds on convex domains of diameter $d$, showing a deficit bound of the form $\Delta(u) \ge c_{1}(p) \left(\frac{\pi_{p}}{d}\right)^{p} d(u,E_{Poin})^{p}$, with a Gaussian analogue for the corresponding optimizer set. The approach hinges on a $C_{p}$-identity for the deficit, the first eigenfunction of the $p$-Laplacian, and weighted log-concave Poincaré inequalities, leveraging Sakaguchi’s concavity result and Colesanti et al.'s geometric framework to obtain explicit geometric constants. Overall, the work provides concrete geometric constants and a rigorous pathway to stability in nonlinear Poincaré inequalities.
Abstract
In this paper, we obtain stability results for the $L^{p}$-Poincaré inequality for both Lebesgue and Gaussian probability measures (Theorem 3.3 and Theorem 3.6). Our approach relies on properties of the first eigenfunction of the (Gaussian) $p$-Laplacian operator and weighted Poincaré inequalities for log-concave measures on convex domains.
