For every inner function Θ, we set Θ*(H2) =def H2⊖ΘH2 and Θ*(HP) =def closHP(HP ∩ Θ*(Hp)) if p ≠ 2. Denote by C P(Θ) the set of all (complex) measures μ, on the closed unit disk double-struck D̄ such that Θ*(Hp) ⊂ L P(|μ|). An inner function Θ is said to be one-component if the set (z ∈ double-struck D:|Θ(z)| < ε) is connected for some ε ∈ (0, 1). A series of criteria for an inner function to be one-component are obtained. For example, it is proved that Θ is one-component if and only if Cp(Θ) does not depend on p ∈ (0,+∞). Moreover, a criterion in terms of reproducing kernels of Θ *(H2) for an inner function Θ to be one-component is obtained. The set CP(Θ) is described in the case where Θ is a Blaschke product of special form. This description implies that the set of all p such that a given measure μ belongs to Cp(Θ) can have any finite or infinite number of connected components. The following examples of interpolating Blaschke products Θ and positive measures μ are constructed: (1) Θ*(H1) ⊂ L1(μ) and Θ*(H2) ⊂ L2(μ) but Θ* (Hp) ⊄ LP(μ) for any p ∈ (1, 2); (2) Θ*(HP) ⊂ Lp(n) if and only if p = 1/n, where n is a positive integer; (3) Θ*(HP) ⊂ L p(μ) if and only if p ≠ 1/n, where n is a positive integer.
| Original language | English |
|---|---|
| Pages (from-to) | 2907-2929 |
| Number of pages | 23 |
| Journal | Journal of Mathematical Sciences |
| Volume | 110 |
| Issue number | 5 |
| DOIs | |
| State | Published - 2002 |
| Externally published | Yes |
ID: 87312078