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arXiv 1802.09074math.NT
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大型树实伽罗瓦表示

Large arboreal Galois representations

Borys Kadets

摘要:

给定域$K$、多项式$f \in K[x]$和适当的元素$t \in K$,迭代$f^{\circ n}$下的$t$的原像集合携带$d$ -ary树的自然结构。研究了$K$的绝对伽罗瓦群通过自同构的全群作用于树的条件。当$K=\mathbb{Q}$,我们展示的例子多项式的每一个偶数次最大伽罗瓦行动的原像树,部分肯定了猜想Odoni。我们还研究了$K=F(t)$和$f \in F[x]$的情形,其中对应的伽罗瓦群是分歧覆盖$f^{\circ n}: \mathbb{P}^1_F \to \mathbb{P}^1_F$的单值群。

英文摘要:

Given a field $K$, a polynomial $f \in K[x]$, and a suitable element $t \in K$, the set of preimages of $t$ under the iterates $f^{\circ n}$ carries a natural structure of a $d$-ary tree. We study conditions under which the absolute Galois group of $K$ acts on the tree by the full group of automorphisms. When $K=\mathbb{Q}$ we exhibit examples of polynomials of every even degree with maximal Galois action on the preimage tree, partially affirming a conjecture of Odoni. We also study the case of $K=F(t)$ and $f \in F[x]$ in which the corresponding Galois groups are the monodromy groups of the ramified covers $f^{\circ n}: \mathbb{P}^1_F \to \mathbb{P}^1_F$.

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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