Second duals of measure algebras

H. G. Dales; A. T.-M. Lau; D. Strauss

  • 2011

Abstract

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Let G be a locally compact group. We shall study the Banach algebras which are the group algebra L¹(G) and the measure algebra M(G) on G, concentrating on their second dual algebras. As a preliminary we shall study the second dual C₀(Ω)” of the C*-algebra C₀(Ω) for a locally compact space Ω, recognizing this space as C(Ω̃), where Ω̃ is the hyper-Stonean envelope of Ω. We shall study the C*-algebra B b ( Ω ) of bounded Borel functions on Ω, and we shall determine the exact cardinality of a variety of subsets of Ω̃ that are associated with B b ( Ω ) . We shall identify the second duals of the measure algebra (M(G),∗) and the group algebra (L¹(G),∗) as the Banach algebras (M(G̃),□ ) and (M(Φ),□ ), respectively, where □ denotes the first Arens product and G̃ and Φ are certain compact spaces, and we shall then describe many of the properties of these two algebras. In particular, we shall show that the hyper-Stonean envelope G̃ determines the locally compact group G. We shall also show that (G̃,□ ) is a semigroup if and only if G is discrete, and we shall discuss in considerable detail the product of point masses in M(G̃). Some important special cases will be considered. We shall show that the spectrum of the C*-algebra L ( G ) is determining for the left topological centre of L¹(G)”, and we shall discuss the topological centre of the algebra (M(G)”,□ ).

How to cite

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H. G. Dales, A. T.-M. Lau, and D. Strauss. Second duals of measure algebras. 2011. <http://eudml.org/doc/286050>.

@book{H2011,
abstract = {Let G be a locally compact group. We shall study the Banach algebras which are the group algebra L¹(G) and the measure algebra M(G) on G, concentrating on their second dual algebras. As a preliminary we shall study the second dual C₀(Ω)” of the C*-algebra C₀(Ω) for a locally compact space Ω, recognizing this space as C(Ω̃), where Ω̃ is the hyper-Stonean envelope of Ω. We shall study the C*-algebra $B^\{b\}(Ω)$ of bounded Borel functions on Ω, and we shall determine the exact cardinality of a variety of subsets of Ω̃ that are associated with $B^\{b\}(Ω)$. We shall identify the second duals of the measure algebra (M(G),∗) and the group algebra (L¹(G),∗) as the Banach algebras (M(G̃),□ ) and (M(Φ),□ ), respectively, where □ denotes the first Arens product and G̃ and Φ are certain compact spaces, and we shall then describe many of the properties of these two algebras. In particular, we shall show that the hyper-Stonean envelope G̃ determines the locally compact group G. We shall also show that (G̃,□ ) is a semigroup if and only if G is discrete, and we shall discuss in considerable detail the product of point masses in M(G̃). Some important special cases will be considered. We shall show that the spectrum of the C*-algebra $L^\{∞\}(G)$ is determining for the left topological centre of L¹(G)”, and we shall discuss the topological centre of the algebra (M(G)”,□ ).},
author = {H. G. Dales, A. T.-M. Lau, D. Strauss},
keywords = {measure algebra; Stone-Čech compactification; group algebra},
language = {eng},
title = {Second duals of measure algebras},
url = {http://eudml.org/doc/286050},
year = {2011},
}

TY - BOOK
AU - H. G. Dales
AU - A. T.-M. Lau
AU - D. Strauss
TI - Second duals of measure algebras
PY - 2011
AB - Let G be a locally compact group. We shall study the Banach algebras which are the group algebra L¹(G) and the measure algebra M(G) on G, concentrating on their second dual algebras. As a preliminary we shall study the second dual C₀(Ω)” of the C*-algebra C₀(Ω) for a locally compact space Ω, recognizing this space as C(Ω̃), where Ω̃ is the hyper-Stonean envelope of Ω. We shall study the C*-algebra $B^{b}(Ω)$ of bounded Borel functions on Ω, and we shall determine the exact cardinality of a variety of subsets of Ω̃ that are associated with $B^{b}(Ω)$. We shall identify the second duals of the measure algebra (M(G),∗) and the group algebra (L¹(G),∗) as the Banach algebras (M(G̃),□ ) and (M(Φ),□ ), respectively, where □ denotes the first Arens product and G̃ and Φ are certain compact spaces, and we shall then describe many of the properties of these two algebras. In particular, we shall show that the hyper-Stonean envelope G̃ determines the locally compact group G. We shall also show that (G̃,□ ) is a semigroup if and only if G is discrete, and we shall discuss in considerable detail the product of point masses in M(G̃). Some important special cases will be considered. We shall show that the spectrum of the C*-algebra $L^{∞}(G)$ is determining for the left topological centre of L¹(G)”, and we shall discuss the topological centre of the algebra (M(G)”,□ ).
LA - eng
KW - measure algebra; Stone-Čech compactification; group algebra
UR - http://eudml.org/doc/286050
ER -

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