3 papers
math.CV2020
Near-isometric duality of Hardy norms with applications to harmonic mappings
Leonid V. Kovalev, Xuerui Yang
Hardy spaces in the complex plane and in higher dimensions have natural finite-dimensional subspaces formed by polynomials or by linear maps. We use the restriction of Hardy norms…
math.CV2019
Algebraic structure of the range of a trigonometric polynomial
Leonid V. Kovalev, Xuerui Yang
The range of a trigonometric polynomial with complex coefficients can be interpreted as the image of the unit circle under a Laurent polynomial. We show that this range is containe…
math.CV2018
Fourier series of circle embeddings
Leonid V. Kovalev, Xuerui Yang
We study the Fourier series of circle homeomorphisms and circle embeddings, with the emphasis on Blaschke product approximation and the vanishing of Fourier coefficients. The analy…