Displaying similar documents to “Interpolating sequences and the Nevanlinna Pick problem.”

Extremal functions of the Nevanlinna-Pick problem and Douglas algebras

V. Tolokonnikov (1993)

Studia Mathematica

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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...

Continuity and convergence properties of extremal interpolating disks.

Pascal J. Thomas (1995)

Publicacions Matemàtiques

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Let a be a sequence of points in the unit ball of Cn. Eric Amar and the author have introduced the nonnegative quantity ρ(a) = infα infk Πj:j≠k dG(αj, αk), where dG is the Gleason distance in the unit disk and the first infimum is taken over all sequences α in the unit disk which map to a by a map from the disk to the ball. ...

The distribution of extremal points for Kergin interpolations : real case

Thomas Bloom, Jean-Paul Calvi (1998)

Annales de l'institut Fourier

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We show that a convex totally real compact set in ℂ n admits an extremal array for Kergin interpolation if and only if it is a totally real ellipse. (An array is said to be extremal for K when the corresponding sequence of Kergin interpolation polynomials converges uniformly (on K ) to the interpolated function as soon as it is holomorphic on a neighborhood of K .). Extremal arrays on these ellipses are characterized in terms of the distribution of the points and the rate of convergence...

Disks extremal with respect to interpolation constants.

Nguyen Van Trao (2000)

Publicacions Matemàtiques

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We define a function μ from the set of sequences in the unit ball to R* by taking the greatest lower bound of the reciprocal of the interpolating constant of the sequences of the disk which get mapped to the given sequence by a holomorphic mapping from the disk to the ball. Its properties are studied in the spirit of the work of Amar and Thomas.

An explicit expression for the K functionals of interpolation between L spaces.

Jesús Bastero, Yves Raynaud, M. Luisa Rezola (1991)

Publicacions Matemàtiques

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When dealing with interpolation spaces by real methods one is lead to compute (or at least to estimate) the K-functional associated to the couple of interpolation spaces. This concept was first introduced by J. Peetre (see [8], [9]) and some efforts have been done to find explicit expressions of it for the case of Lebesgue spaces. It is well known that for the couple consisting of L1 and L∞ on [0, ∞) K is given by K (t; f, L1,...