We give several characterizations of the symmetrized n-disc Gₙ which generalize to the case n ≥ 3 the characterizations of the symmetrized bidisc that were used in order to solve the two-point spectral Nevanlinna-Pick problem in ℳ ₂(ℂ). Using these characterizations of the symmetrized n-disc, which give necessary and sufficient conditions for an element to belong to Gₙ, we obtain necessary conditions of interpolation for the general spectral Nevanlinna-Pick problem. They also allow us to give a method to construct analytic functions from the open unit disc of ℂ into Gₙ and to obtain some of the complex geodesics on Gₙ.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm170-1-2, author = {Constantin Costara}, title = {On the spectral Nevanlinna-Pick problem}, journal = {Studia Mathematica}, volume = {166}, year = {2005}, pages = {23-55}, zbl = {1074.30035}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm170-1-2} }
Constantin Costara. On the spectral Nevanlinna-Pick problem. Studia Mathematica, Tome 166 (2005) pp. 23-55. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm170-1-2/