On interpolation with finite Blaschke products

In this talk, we discuss an alternative proof of the Jones-Ruscheweyh theorem concerning boundary interpolation with finite Blaschke products. The approach is based on Positivstellensatz by Prestel and Delzell and a representation of positive polynomials in a special form due to Berr and Wörmann together with a particular structure of equations.
This is based on joint work with Béla Nagy.