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This article is cited in 35 scientific papers (total in 35 papers)
A version of van der Waerden's theorem and a proof of Mishchenko's
conjecture on homomorphisms of locally compact groups
A. I. Shtern M. V. Lomonosov Moscow State University
Abstract:
van der Waerden proved in 1933 that every finite-dimensional locally
bounded representation of a semisimple compact Lie group is automatically
continuous. This theorem evoked an extensive literature, which related
the assertion of the theorem (and its converse) to properties of Bohr
compactifications of topological groups and led to the introduction
and study of classes of so-called van der Waerden groups and algebras.
In the present paper we study properties of (not necessarily continuous)
locally relatively compact homomorphisms of topological groups
(in particular, connected locally compact groups) from the point
of view of this theorem and obtain a classification
of homomorphisms of this kind from the point of view of their continuity
or discontinuity properties (this classification is especially simple
in the case of Lie groups because it turns out that every locally
bounded finite-dimensional representation of a connected Lie group
is continuous on the commutator subgroup). Our main
results are obtained by studying new objects, namely, the discontinuity
group and the final discontinuity group of a locally bounded homomorphism,
and the new notion of a finally continuous homomorphism from one locally
compact group into another.
The notion of local relative compactness of a homomorphism
is naturally related to the notion of point oscillation
(at the identity element of the group) introduced by the
author in 2002. According to a conjecture of A. S. Mishchenko,
the (reasonably defined) oscillation at a point of any
finite-dimensional representation of a ‘good’ topological group
can take one of only three values: $0$, $2$ and $\infty$.
We shall prove this for all connected locally compact groups.
Received: 14.12.2006
Citation:
A. I. Shtern, “A version of van der Waerden's theorem and a proof of Mishchenko's
conjecture on homomorphisms of locally compact groups”, Izv. Math., 72:1 (2008), 169–205
Linking options:
https://www.mathnet.ru/eng/im2599https://doi.org/10.1070/IM2008v072n01ABEH002397 https://www.mathnet.ru/eng/im/v72/i1/p183
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Abstract page: | 970 | Russian version PDF: | 290 | English version PDF: | 22 | References: | 92 | First page: | 5 |
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