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arXiv 0811.0236math.AT
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关于Out(F_{2(p-1)})的模p上同调

On the mod - p cohomology of Out(F_{2(p-1)}

Henry Glover, Hans-Werner Henn

摘要:

本文研究了自由群F_n的外自同构群Out(F_n)在n=2(p-1)的情况下的模p上同调.当p=3时,我们给出了一个完整的计算,至少在Out(F_4)的虚上同调维数(它是5)以上。更精确地,我们计算了外层空间p-奇异部分的等变上同调,其中p=3。对于一般素数p>3,我们用Aut(F_k)的mod-p上同调给出了一个递归描述,其中k ≤ p-1。在这种情况下,我们使用Out(F_n)的基本阿贝尔p-子群偏序集的Out(F_{2(p-1)})-等变上同调。

英文摘要:

We study the mod-p cohomology of the group Out(F_n) of outer automorphisms of the free group F_n in the case n=2(p-1) which is the smallest n for which the p-rank of this group is 2. For p=3 we give a complete computation, at least above the virtual cohomological dimension of Out(F_4) (which is 5). More precisley, we calculate the equivariant cohomology of the p-singular part of outer space for p=3. For a general prime p>3 we give a recursive description in terms of the mod-p cohomology of Aut(F_k) for k less or equal to p-1. In this case we use the Out(F_{2(p-1)})-equivariant cohomology of the poset of elementary abelian p-subgroups of Out(F_n).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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