A Schwarz lemma for the symmetrized tridisc and description of interpolating functions

Abstract: We produce a Schwarz lemma for the symmetrized tridisc [ \mathbb G_3 ={ (z_1+z_2+z_3,z_1z_2+z_2z_3+z_3z_1,z_1z_2z_3): \,|z_i|< 1, i=1,2,3 }. ] We show that an interpolating function related to the Schward lemma for $\mathbb G_3$ is not unique and present an explicit description of all such interpolating functions. We also study the complex geometry of $\mathbb G_3$ and present a variety of new characterizations for the open and closed symmetrized tridisc.