Index realization for automorphisms of free groups
Index realization for automorphisms of free groups
复制标题
自由群自同构的索引实现
DOI:
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发表时间:
2015
期刊:
影响因子:
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通讯作者:
M. Lustig
中科院分区:
文献类型:
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作者:
T. Coulbois;M. Lustig
For any surface $Sigma$ of genus $g geq 1$ and (essentially) any collection of positive integers $i_1, i_2, ldots, i_ell$ with $i_1+cdots +i_ell = 4g-4$ Masur and Smillie have shown that there exists a pseudo-Anosov homeomorphism $h:Sigma o Sigma$ with precisely $ell$ singularities $S_1, ldots, S_ell$ in its stable foliation $cal L$, such that $cal L$ has precisely $i_k+2$ separatrices raying out from each $S_k$.
In this paper we prove the analogue of this result for automorphisms of a free group $F_N$, where "pseudo-Anosov homeomorphism" is replaced by "fully irreducible automorphism" and the Gauss-Bonnet equality $i_1+cdots +i_ell = 4g-4$ is replaced by the index inequality $i_1+cdots +i_ell leq 2N-2$ from Gaboriau, Jaeger, Levitt and Lustig.