Differentiable Actions on 2 « - Spheres
نویسندگان
چکیده
Introduction. It is shown in [4] that there is an infinite family of semifree Zm actions on odd dimensional homotopy spheres. There is also an infinite family of semifree S actions on odd dimensional homotopy spheres (see [2], [5]). On the other hand, it is announced in [2] that there are only finitely many inequivalent semifree S actions on even dimensional homotopy spheres. Hence it is interesting to know whether the same phenomenon occurs for Zm actions. The study of the AtiyahSinger G-signature theorem and an exact sequence of M. Rothenberg leads to the discovery of an infinite family of semifree Zm actions on even dimensional homotopy spheres which, to the best of author's knowledge, is not previously known. The main result is the following:
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