Extensions and Selections in Subspaces of C(K).
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J. Globevnik (1980)
Monatshefte für Mathematik
Robert L. Blair (1981)
Czechoslovak Mathematical Journal
Antonio Fernández, M. Florencio, Pedro J. Paúl, Vladimir Müller (1989)
Collectanea Mathematica
V. Tolokonnikov (1993)
Studia Mathematica
The Nevanlinna-Pick problem at the zeros of a Blaschke product B having a solution of norm smaller than one is studied. All its extremal solutions are invertible in the Douglas algebra D generated by B. If B is a finite product of sparse Blaschke products (Newman Blaschke products, Frostman Blaschke products) then so are all the extremal solutions. For a Blaschke product B a formula is given for the number C(B) such that if the NP-problem has a solution of norm smaller than C(B) then all its extremal...
Harish Chandra, Bina Singh (2010)
Matematički Vesnik
Anthony W. Hager, Lewis C. Robertson (1978)
Rendiconti del Seminario Matematico della Università di Padova
Alex Heinis, Jan Wiegerinck (2000)
Annales Polonici Mathematici
We study the extreme and exposed points of the convex set consisting of representing measures of the disk algebra, supported in the closed unit disk. A boundary point of this set is shown to be extreme (and even exposed) if its support inside the open unit disk consists of two points that do not lie on the same radius of the disk. If its support inside the unit disk consists of 3 or more points, it is very seldom an extreme point. We also give a necessary condition for extreme points to be exposed...
Per Roar Andenaes (1977)
Mathematica Scandinavica
M. Solveig Espelie (1980)
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze
Przemysław Kajetanowicz (1984)
Colloquium Mathematicae
Gerd Niestegge (1983)
Mathematische Annalen
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