Abstract from the Pacific Journal of Mathematics

Volume 180, Number 2, October 1997

Title: Riemann Sums and Modular Functions on Locally Compact Groups

Authors: Kenneth A. Ross and George Willis

Abstract:

In 1967 the first author and Karl Stromberg published a theorem concerning generalized limits of Riemann sums on locally compact groups. The setting is a locally compact group G and an increasing sequence H_n of closed subgroups whose union is dense in G. The theorem was shown to hold provided that the restriction of the modular function on G to H_n agrees with the modular function of H_n for all large n. This hypothesis holds in many cases and, in fact, Ross and Stromberg were unable to determine whether the hypothesis was really needed for the theorem or even whether this hypothesis always holds. An example is provided which shows that this hypothesis does not always hold. It is then shown that the theorem fails without the hypothesis.

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