Journal of the London Mathematical Society Advance Access originally published online on May 12, 2009
Journal of the London Mathematical Society 2009 80(1):55-71; doi:10.1112/jlms/jdp011
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© 2009 London Mathematical Society
Uniform continuity over locally compact quantum groups
Department of Mathematical and Statistical Sciences
University of Alberta
Edmonton, Alberta
Canada T6G 2G1
http://www.math.ualberta.ca/~runde/
We define, for a locally compact quantum group
in the sense of Kustermans–Vaes, the space of LUC(
) of left uniformly continuous elements in L
(
). This definition covers both the usual left uniformly continuous functions on a locally compact group and Granirer's uniformly continuous functionals on the Fourier algebra. We show that LUC(
) is an operator system containing the C*-algebra
0(
) and contained in its multiplier algebra
(
0(
)). We use this to partially answer an open problem by Bédos–Tuset: if
is co-amenable, then the existence of a left invariant mean on
(
0(
)) is sufficient for
to be amenable. Furthermore, we study the space WAP(
) of weakly almost periodic elements of L
(
): it is a closed operator system in L
(
) containing
0(
) and, for co-amenable
, contained in LUC(
). Finally, we show that, under certain conditions, which are always satisfied if
is a group, the operator system LUC(
) is a C*-algebra.
2000 Mathematics Subject Classification 46L89 (primary); 43A07, 46L07, 46L65, 47L25, 47L50, 81R15 (secondary).
This research supported by NSERC.
Received February 14, 2008; revised September 2, 2008; published online May 12, 2009.