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On critical pairs of product sets in a certain matrix group

Published online by Cambridge University Press:  24 October 2008

M. McCrudden
Affiliation:
University of Birmingham

Extract

1. Introduction. If G is a locally compact Hausdorff topological group, and μ is (left) Haar measure on G, then we denote by ℬ(G) the class of all Borel subsets of G having finite measure, and by VG the set {μ(E): E ∊ ℬ(G)} of real numbers. The product set function of G, ΦG: VG × VGVG, is defined (see (4) and (5)) by

and, for each u, vVG, we call a pair (E, F) of Borel subsets of G a critical (u, v)-pair, if μ(E) = u, μ(F) = v, and μ*(EF) = ΦG(u, v). We denote the class of all critical (u, v)-pairs by and we write ℰG for .

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1970

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References

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