Abstract

Let K be affine, that is, \\in {\mathbb {R}}^{n+m}: y_{1}=\cdots =y_{m}=0\}\). We compute the sharp constant of Hardy inequality related to the distance d for polyharmonic operator. Moreover, we show that there exists a constant \ such that for each \\), there holds $$\begin{aligned} \int _{{\mathbb {R}}^{n+m}}|\nabla ^{k} u|^{2}\mathrm{d}x\mathrm{d}y-c_{m,k}\int _{{\mathbb {R}}^{n+m}}\frac{u^{2}}{|y|^{2k}}\mathrm{d}x\mathrm{d}y\ge C\left ^{\frac{n+m-2k}{n+m}}, \end{aligned}$$where \, \}{n+m-2k}\), \p}{2}-n-m\) and \ is the sharp Hardy constant. These inequalities generalize the result of Maz’ya ) and Lu and the second author for polyharmonic operators). In order to prove the main result, we establish some Poincaré–Sobolev inequalities on hyperbolic space which is of independent interest.