The expansion factors of an outer automorphism and its inverse
The expansion factors of an outer automorphism and its inverse
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外自同构及其逆的展开因子
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
L. Mosher
中科院分区：
文献类型：
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作者：
M. Handel;L. Mosher
秩为n的自由群Fn的全不可约外自同构o的扩张因子通常与o-1的扩张因子不同。然而，我们证明了o和o-1的扩张因子的乘积之比在上界有一个仅取决于秩n的常数。我们还证明了一个更一般的定理，适用于Fn的任意外自同构及其逆和它们的两个谱的扩展因子。
A fully irreducible outer automorphism o of the free group F n of rank n has an expansion factor which often differs from the expansion factor of o -1 Nevertheless, we prove that the ratio between the logarithms of the expansion factors of o and o -1 is bounded above by a constant depending only on the rank n. We also prove a more general theorem applying to an arbitrary outer automorphism of F n and its inverse and their two spectrums of expansion factors.