Time: | 3:30pm - 4:30 pm |
Room: |
Wean Hall 8220
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Speaker: |
Joseph Zielinski Department of Mathematical Sciences CMU |
Title: |
Roelcke precompact sets in Polish groups
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Abstract: |
In these talks we first recall the uniform structures associated to a topological group. We then present J. Roe's notion of a coarse space, and consider compatible coarse structures on groups with emphasis on the 'left-coarse structure' of a topological group introduced by C. Rosendal. Associated to this notion are the 'locally bounded Polish groups': those for which the left-coarse structure is the bounded coarse structure of some compatible, left-invariant metric. Next, we introduce the Roelcke precompact subsets of a Polish group, which admit equivalent natural definitions both in terms of the lower uniformity on the group and as a subideal of the bounded sets in the left-coarse structure. Through this we define the 'locally Roelcke precompact Polish groups' — a subfamily of the locally bounded Polish groups — and present various examples, applications, and several characterizations of these groups. |