Uniform Approximation by Indestructible Blaschke Products
We address the question: Are the inner functions in the uniform closure in the algebra of bounded analytic functions of the indestructible Blaschke products? We show, in particular, that every inner function with countable spectrum is in the closure of the indestructible Blaschke products, that every Blaschke product is a product of two indestructible Blaschke products and we study approximation in modulus.
Journal of Mathematical Analysis and its Applications
Gorkin, Pamela and Akeroyd, John. "Uniform Approximation by Indestructible Blaschke Products." Journal of Mathematical Analysis and its Applications (2016) : 1419-1434.