Schwarz-contractivity of the Poisson operator

Leonid V. Kovalev

We say that the Poisson operator $P_r$ is Schwarz-contractive from a space $X$ to a space $Y$ if $\Vert P_r{\Vert }_{X\to Y}\le r$ holds for all $0<r<1$. The classical Schwarz lemma is the c…