Abstract
We prove that arbitrary homomorphisms from one of the groups
into a separable group are automatically continuous. This has consequences for the representations of these groups as discrete groups. For example, it follows, in combination with a result of V. G. Pestov, that any action of the discrete group Homeo+(ℝ) by homeomorphisms on a compact metric space has a fixed point.
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Research of the second author was supported by NSF grant DMS-0400931.
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Rosendal, C., Solecki, S. Automatic continuity of homomorphisms and fixed points on metric compacta. Isr. J. Math. 162, 349–371 (2007). https://doi.org/10.1007/s11856-007-0102-y
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DOI: https://doi.org/10.1007/s11856-007-0102-y