Schwarz-Pick type inequalities from an operator theoretical point of view

TL;DR

This paper derives generalized Schwarz-Pick inequalities using operator theory, connecting classical function theory with modern Hilbert space techniques, and extends results to polydisks and higher derivatives.

Contribution

It provides an operator-theoretic proof of Schwarz-Pick inequalities and extends these results to multivariable and higher order cases.

Findings

Operator-theoretic proofs of Schwarz-Pick inequalities

Generalization to polydisks and higher derivatives

Enhanced Schwarz-Pick lemma using distinguished varieties

Abstract

We use (versions of) the von Neumann inequality for Hilbert space contractions to prove several Schwarz-Pick inequalities. Specifically, we derive an alternate proof for a multi-point Schwarz-Pick inequality by Beardon and Minda, along with a generalized version for operators. Connections with model spaces and Peschl's invariant derivatives are established. Finally, Schwarz-Pick inequalities for analytic functions on polydisks and for higher order derivatives are discussed. An enhanced version of the Schwarz-Pick lemma, using the notion of distinguished variety, is obtained for the bidisk.