Unital Compact Homomorphisms between Extended Analytic Lipschitz Algebras

Let 𝑋 and 𝐾 be compact plane sets with 𝐾⊆𝑋. We define 𝐴(𝑋,𝐾)={𝑓∈𝐶(𝑋)∶𝑓|𝐾∈𝐴(𝐾)}, where 𝐴(𝐾)={𝑔∈𝐶(𝑋)∶𝑔 is analytic on int(𝐾)}. For 𝛼∈(0,1], we define Lip(𝑋,𝐾,𝛼)={𝑓∈𝐶(𝑋)∶𝑝𝛼,𝐾(𝑓)=sup{|𝑓(𝑧)−𝑓(𝑤)|/|𝑧−𝑤|𝛼∶𝑧,𝑤∈𝐾,𝑧≠𝑤}<∞} and Lip𝐴(𝑋,𝐾,𝛼)=𝐴(𝑋,𝐾)∩Lip(𝑋,𝐾,𝛼). It is known that Lip𝐴(𝑋,𝐾,𝛼) is a natural Banach f...

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Bibliographic Details
Main Authors: Davood Alimohammadi, Maliheh Mayghani
Format: Article
Language:English
Published: Wiley 2011-01-01
Series:Abstract and Applied Analysis
Online Access:http://dx.doi.org/10.1155/2011/146758
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Summary:Let 𝑋 and 𝐾 be compact plane sets with 𝐾⊆𝑋. We define 𝐴(𝑋,𝐾)={𝑓∈𝐶(𝑋)∶𝑓|𝐾∈𝐴(𝐾)}, where 𝐴(𝐾)={𝑔∈𝐶(𝑋)∶𝑔 is analytic on int(𝐾)}. For 𝛼∈(0,1], we define Lip(𝑋,𝐾,𝛼)={𝑓∈𝐶(𝑋)∶𝑝𝛼,𝐾(𝑓)=sup{|𝑓(𝑧)−𝑓(𝑤)|/|𝑧−𝑤|𝛼∶𝑧,𝑤∈𝐾,𝑧≠𝑤}<∞} and Lip𝐴(𝑋,𝐾,𝛼)=𝐴(𝑋,𝐾)∩Lip(𝑋,𝐾,𝛼). It is known that Lip𝐴(𝑋,𝐾,𝛼) is a natural Banach function algebra on 𝑋 under the norm ||𝑓||Lip(𝑋,𝐾,𝛼)=||𝑓||𝑋+𝑝𝛼,𝐾(𝑓), where ||𝑓||𝑋=sup{|𝑓(𝑥)|∶𝑥∈𝑋}. These algebras are called extended analytic Lipschitz algebras. In this paper we study unital homomorphisms from natural Banach function subalgebras of Lip𝐴(𝑋1,𝐾1,𝛼1) to natural Banach function subalgebras of Lip𝐴(𝑋2,𝐾2,𝛼2) and investigate necessary and sufficient conditions for which these homomorphisms are compact. We also determine the spectrum of unital compact endomorphisms of Lip𝐴(𝑋,𝐾,𝛼).
ISSN:1085-3375
1687-0409