Explicit examples of finite subgroups of the group of homotopy classes of self-homotopy equivalences of some flat Riemannian manifolds which cannot be lifted to effective actions are given. It is also shown that no finite subgroups of the kernel of [pi]0(Homeo(M))-->Out [pi]1(M) can be lifted back to Homeo(M), for a large class of flat manifolds M. Some results of an earlier paper by the authors are refined and related to recent work of R. Schoen and S.T. Yau.
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机译：给出了一些平坦的黎曼流形的同伦等价的同伦类的同伦类组的有限子组的显式实例，该类不能提升为有效的作用。还显示出，对于一大类平面流形来说，π0（Homeo（M））-> Out pi1（M）的核的有限子群不能被提升回Homeo（M）。 M.作者的早期论文的一些结果已得到完善，并与R. Schoen和ST的最新工作有关au
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