Self-mappings of the quaternionic unit ball: Multiplier properties, the schwarz-pick inequality, and the nevanlinna-pick interpolation problem

We study several aspects concerning slice regular functions mapping the quaternionic open unit ball into itself. We characterize these functions in terms of their Taylor coefficients at the origin and identify them as contractive multipliers of the Hardy space H2(B). In addition, we formulate and solve the Nevanlinna-Pick interpolation problem in the class of such functions presenting necessary and sufficient conditions for the existence and for the uniqueness of a solution. Finally, we describe all solutions to the problem in the indeterminate case. As an application, we establish the Schwarz-Pick inequality for slice regular self-mappings of.