The weighted Hardy constant

Abstract

Let $\Omega$ be a domain in $R^d$ and $d_\Gamma$ the Euclidean distance to the boundary $\Gamma$. We investigate whether the weighted Hardy inequality \[ \|d_\Gamma^{\delta/2-1}\varphi\|_2\leq a_\delta\,\|d_\Gamma^{\delta/2}\,(\nabla\varphi)\|_2 \] is valid, with $\delta\geq 0$ and $a_\delta>0$, for all $\varphi\in C_c^1(\Gamma_r)$ and all small $r>0$ where $\Gamma_r=\{x\in\Omega: d_\Gamma(x) 1$ but if $\delta\in[0,1\rangle$ then $a_\delta(\Gamma)$ can be strictly larger than $2/|\delta-1|$. Finally we use these results to establish self-adjointness criteria for degenerate elliptic diffusion operators.