Convexity around the Unit of a Banach Algebra
| Data(s) |
21/07/2016
21/07/2016
2008
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|---|---|
| Resumo |
2000 Mathematics Subject Classification: Primary: 46B20. Secondary: 46H99, 47A12. We estimate the (midpoint) modulus of convexity at the unit 1 of a Banach algebra A showing that inf {max±||1 ± x|| − 1 : x ∈ A, ||x||=ε} ≥ (π/4e)ε²+o(ε²) as ε → 0. We also give a characterization of two-dimensional subspaces of Banach algebras containing the identity in terms of polynomial inequalities. |
| Identificador |
Serdica Mathematical Journal, Vol. 34, No 3, (2008), 619p-628p 1310-6600 |
| Idioma(s) |
en |
| Publicador |
Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| Palavras-Chave | #Unital Banach Algebra #Strongly Extreme Point #Midpoint Modulus of Local Convexity |
| Tipo |
Article |
