Rank of truncated Hankel operators on model spaces

Abstract

We study the rank of truncated Hankel operators on model spaces $K^2_u := H^2 \ominus uH^2$. Concrete rank formulas will be established for several classes of finite rank truncated Hankel operators. The rank formulas will be derived seperately depending on whether the model space $K^2_u$ is finite-dimensional, or, infinite-dimensional.