And the Phan-type Theorem of Type F 4
And the Phan-type Theorem of Type F 4
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以及F型4的Phan型定理
DOI:
10.1090/s0002-9947-2012-05694-7
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发表时间:
2009
期刊:
影响因子:
--
通讯作者:
Stefan Witzel
中科院分区:
文献类型:
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作者:
Stefan Witzel
We adapt and refine the methods developed in [Abr96] and [DGM] in order to establish the sphericity of the Phan geometries defined in [BGHS07] (type Bn) and [GHS03] (type Cn), and their generalizations. As applications of this sphericity we determine the topological finiteness length of the unitary form of the group Sp 2n (F q2 [t, t]) (Theorem 7.1) and give the first published proof of the Phan-type theorem of type F4 (Theorem 7.11). Apart from that we reproduce the topological finiteness length of the group Sp 2n (F q2 [t]) and the Phan-type theorems of types Bn and Cn. In the theory of arithmetic groups our result on the topological finiteness length of the unitary form of Sp 2n (F q2 [t, t]) is another example supporting the rank conjecture, see [Beh98, p. 80]. Within the revision of the classification of the finite simple groups this publication of the Phan-type theorem of type F4 concludes the revision of Phan’s theorems [Pha77a], [Pha77b] and their extension to the non-simply laced diagrams; cf. [AB08, Section 14.2] on page 656 and [GLS05] on page 333.