arXiv 1602.090092016-02math.LOmath.GNmath.GR

Equivalence relations invariant under group actions

Tomasz Rzepecki

备注：: 23 pages, streamlined version
发表信息：: J. Symbolic Logic 83.2 (2018), pp. 683-702
DOI：: 10.1017/jsl.2017.88

英文摘要：

We extend some recent results about bounded invariant equivalence relations and invariant subgroups of definable groups: we show that type-definability and smoothness are equivalent conditions in a wider class of relations than heretofore considered, which includes all the cases for which the equivalence was proved before. As a by-product, we show some analogous results in purely topological context (without direct use of model theory).

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