Research output: Contribution to journal › Article › peer-review
Isometric embeddings of the spaces KΘ in the upper half-plane. / Baranov, A.
In: Journal of Mathematical Sciences, Vol. 105, No. 5, 01.01.2001, p. 2319-2329.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Isometric embeddings of the spaces KΘ in the upper half-plane
AU - Baranov, A.
PY - 2001/1/1
Y1 - 2001/1/1
N2 - Let Θ be an interior function in the upper half-plane. Positive measures μ on the real line ℝ such that ∫ℝ|f| 2dμ = ∥f∥2 2 for all f ∈ K Θ = H2 ⊖ΘH2 (i.e., the embedding KΘ ⊂ L2(μ) is isometric) are studied. A similar problem for the unit disk was considered by A. B. Aleksandrov. In the case of the upper half-plane and special interior functions, such measures were described by De Branges. The goal of this paper is to explain why these results are essentially different. As is shown, the fact that the isomterty fails is connected with the existence of the finite angular derivative and can be expressed in terms of factorization parameters of Θ. Owing to this results, it is possible to formulate a criterion (in terms of zeros of the generating entire function E) for an orthogonal system of reproducing kernels to be a basis for the space H(E).
AB - Let Θ be an interior function in the upper half-plane. Positive measures μ on the real line ℝ such that ∫ℝ|f| 2dμ = ∥f∥2 2 for all f ∈ K Θ = H2 ⊖ΘH2 (i.e., the embedding KΘ ⊂ L2(μ) is isometric) are studied. A similar problem for the unit disk was considered by A. B. Aleksandrov. In the case of the upper half-plane and special interior functions, such measures were described by De Branges. The goal of this paper is to explain why these results are essentially different. As is shown, the fact that the isomterty fails is connected with the existence of the finite angular derivative and can be expressed in terms of factorization parameters of Θ. Owing to this results, it is possible to formulate a criterion (in terms of zeros of the generating entire function E) for an orthogonal system of reproducing kernels to be a basis for the space H(E).
UR - http://www.scopus.com/inward/record.url?scp=7444257251&partnerID=8YFLogxK
U2 - 10.1023/A:1011309128229
DO - 10.1023/A:1011309128229
M3 - Article
AN - SCOPUS:7444257251
VL - 105
SP - 2319
EP - 2329
JO - Journal of Mathematical Sciences
JF - Journal of Mathematical Sciences
SN - 1072-3374
IS - 5
ER -
ID: 32721389