On generalizations of Lavrentieff’s theorem for Polish group actions
On generalizations of Lavrentieff’s theorem for Polish group actions
复制标题
DOI：
10.1090/s0002-9947-06-03991-2
复制
发表时间：
2006-08
影响因子：
1.3
通讯作者：
Longyun Ding;Su Gao
中科院分区：
文献类型：
--
作者：
Longyun Ding;Su Gao
证明了对每个非局部紧的Polish群G，存在G在Polish空间X的n × 11-完备子集A上的连续作用a，使得a不能扩张到X中A的任何超集.这回答了Becker和Kechris提出的一个问题，并表明他们的一个较早的定理在几个方面是最优的。
It is shown that for every Polish group G that is not locally compact there is a continuous action a of G on a Π 1 1 -complete subset A of a Polish space X such that a cannot be extended to any superset of A in X. This answers a question posed by Becker and Kechris and shows that an earlier theorem of them is optimal in several aspects.