A symmetry property for polyharmonic functions vanishing on equidistant hyperplanes

Ognyan Kounchev, Hermann Render

Let $u\left(t,y\right)$ be a polyharmonic function of order $N$ defined on the strip $\left(a,b\right)\times {\mathbb{R}}^d$ satisfying the growth condition $$ \sup_{t\in K}\lef…