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The size of the quotient LUC(G)/UC(G)

  • Mahmoud Filali EMAIL logo and Pekka Salmi
Published/Copyright: April 14, 2010
Forum Mathematicum
From the journal Volume 23 Issue 3

Abstract

We consider the Banach space LUC(G) (RUC(G)) of the bounded left (right) uniformly continuous functions on a locally compact group G, the Banach space UC(G) = LUC(G)∩RUC(G) of the bounded uniformly continuous functions on G and the quotient Banach space LUC(G)/UC(G). If G is a sin group, that is, the right and the left uniformities coincide, then the quotient LUC(G)/UC(G) is trivial, so we are concerned with non-sin groups. We bring up the topological structure of G to the Banach space structure of the quotient by showing first that when the compact covering number k(G) is greater than or equal to the local weight b(G), there is a linear isometric copy of in LUC(G)/UC(G). Then, using the generalised Kakutani–Kodaira theorem due to Zhiguo Hu, we deduce that in the case of a general non-sin group, there exists a compact normal subgroup N of G such that ℵ0b(G/N) ≤ k(G) and LUC(G)/UC(G) contains a linear isometric copy of .

Received: 2008-09-04
Revised: 2009-06-26
Published Online: 2010-04-14
Published in Print: 2011-May

© de Gruyter 2011

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