1. On Dynamical Cancellation.
- Author
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Bell, Jason P, Matsuzawa, Yohsuke, and Satriano, Matthew
- Subjects
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ENDOMORPHISMS , *INTEGERS , *POLYNOMIALS - Abstract
Let |$X$| be a projective variety and let |$f$| be a dominant endomorphism of |$X$| , both of which are defined over a number field |$K$|. We consider a question of the 2nd author, Meng, Shibata, and Zhang, who asks whether the tower of |$K$| -points |$Y(K)\subseteq (f^{-1}(Y))(K)\subseteq (f^{-2}(Y))(K)\subseteq \cdots $| eventually stabilizes, where |$Y\subset X$| is a subvariety invariant under |$f$|. We show this question has an affirmative answer when the map |$f$| is étale. We also look at a related problem of showing that there is some integer |$s_0$| , depending only on |$X$| and |$K$| , such that whenever |$x, y \in X(K)$| have the property that |$f^{s}(x) = f^{s}(y)$| for some |$s \geqslant 0$| , we necessarily have |$f^{s_{0}}(x) = f^{s_{0}}(y)$|. We prove this holds for étale morphisms of projective varieties, as well as self-morphisms of smooth projective curves. We also prove a more general cancellation theorem for polynomial maps on |${\mathbb {P}}^1$| where we allow for composition by multiple different maps |$f_1,\dots ,f_r$|. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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