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Geometry Colloquium
Seminar information archive ～04/19｜Next seminar｜Future seminars 04/20～
| Date, time & place | Friday 10:00 - 11:30 126Room #126 (Graduate School of Math. Sci. Bldg.) |
|---|
2013/05/09
10:00-11:30 Room #122 (Graduate School of Math. Sci. Bldg.)
KIDA Yoshikata (Kyoto University)
Rigidity for amalgamated free products and their envelopes (JAPANESE)
KIDA Yoshikata (Kyoto University)
Rigidity for amalgamated free products and their envelopes (JAPANESE)
[ Abstract ]
For a discrete countable group L, we mean by an envelope of L a locally compact second countable group having a lattice isomorphic to L. In general, it is quite hard to describe all envelopes of a given L. This problem is closely related to orbit equivalence between probability-measure-preserving actions of groups, and also related to Mostow type rigidity. I explain a fundamental idea to attack this problem, and give examples of groups for which the problem is solved. The examples contain mapping class groups of surfaces and certain amalgamated free products. An outline to get an answer for the latter groups will be discussed.
For a discrete countable group L, we mean by an envelope of L a locally compact second countable group having a lattice isomorphic to L. In general, it is quite hard to describe all envelopes of a given L. This problem is closely related to orbit equivalence between probability-measure-preserving actions of groups, and also related to Mostow type rigidity. I explain a fundamental idea to attack this problem, and give examples of groups for which the problem is solved. The examples contain mapping class groups of surfaces and certain amalgamated free products. An outline to get an answer for the latter groups will be discussed.
