Unitary Banach algebras

Julio Becerra Guerrero, Simon Cowell, Ángel Rodríguez Palacios, Geoffrey V. Wood

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


In a Banach algebra an invertible element which has norm one and whose inverse has norm one is called unitary. The algebra is unitary if the closed convex hull of the unitary elements is the closed unit ball. The main examples are the C*-algebras and the l1 group algebra of a group. In this paper, different characterizations of unitary algebras are obtained in terms of numerical ranges, dentability and holomorphy. In the process some new characterizations of C*-algebras are given.

Original languageEnglish
Pages (from-to)25-51
Number of pages27
JournalStudia Mathematica
Issue number1
Publication statusPublished - 2004

ASJC Scopus subject areas

  • General Mathematics


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