面积型的Nevanlinna类上的复合算子

Composition Operators Between Area-Type Nevanlinna Classes

设Npa是面积型的Nevanlinna类.研究了Npa上的复合算子,主要通过建立面积型Nevanlinna类上的Carleson测度不等式而给出了复合算子Cφ:Npa→Nqa(1<p≤q)为有界(或紧)算子的充分必要条件.此外,还给出了Npa上可逆及Fredholm复合算子的特征.

Composition operators C_φ on area-type Nevanlinna classes N^p_a are studied. We give some sufficient and necessary conditions by constructing the Carleson inequality on N^p_a, for composition operator C_φ:N^p_a→ N^q_a(1<p≤q) to be bounded or compact. In addition, we also characterize the inducing maps which induce invetible or Fredholm composition operators on N^p_a.