Sub-Hardy Hilbert Spaces in the Unit Disk

This up-to-date account brings together results previously scattered throughout the literature as well as new material in the area of function theory. The focus is on describing some of what has been learned thus far about the structure of the de Branges-Rovnyak spaces and their function-theoretic connections. Hilbert Spaces Inside Hilbert Spaces.

Hilbert Spaces Inside H?.

Cauchy Integral Representations.

Nonextreme Points.

Extreme Points.

Angular Derivatives.

Higher Derivatives.

Equality of H(b) and H().

Equality of H(b) and M(a).

Near Equality of H(b) and M(a).

Brief Mention of a Few Additional Topics.

References.

Supplementary References.

Index.

Donald Erik Sarason was an American mathematician who made fundamental advances in the areas of Hardy space theory and VMO. He was one of the most popular doctoral advisors in the Mathematics Department at UC Berkeley. He supervised 39 Ph.D. theses at UC Berkeley.