A sparsity result for the Dynamical Mordell-Lang Conjecture in positive characteristic

We prove a quantitative partial result in support of the Dynamical Mordell-Lang Conjecture (also known as the DML conjecture) in positive characteristic. More precisely, we show the following: given a field $K$ of characteristic $p$, given a semiabelian variety $X$ defined over a finite subfield of...

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Bibliographic Details
Main Authors: Ghioca, Dragos, Ostafe, Alina, Saleh, Sina, Shparlinski, Igor E.
Format: Article in Journal/Newspaper
Language:unknown
Published: arXiv 2020
Subjects:
DML
Online Access:https://dx.doi.org/10.48550/arxiv.2012.13711
https://arxiv.org/abs/2012.13711
Description
Summary:We prove a quantitative partial result in support of the Dynamical Mordell-Lang Conjecture (also known as the DML conjecture) in positive characteristic. More precisely, we show the following: given a field $K$ of characteristic $p$, given a semiabelian variety $X$ defined over a finite subfield of $K$ and endowed with a regular self-map $Φ:X \longrightarrow X$ defined over $K$, given a point $α\in X(K)$ and a subvariety $V\subseteq X$, then the set of all non-negative integers $n$ such that $Φ^n(α)\in V(K)$ is a union of finitely many arithmetic progressions along with a subset $S$ with the property that there exists a positive real number $A$ (depending only on $N$, $Φ$, $α$, $V$) such that for each positive integer $M$, we have $$\#\left\{n\in S\colon~ n\le M\right\}\le A\cdot \left(1+\log M\right)^{\dim V}.$$