Dynamical Mordell–Lang conjecture (generic orbit form)

Prove that for any projective variety X over the algebraic closure of Q, any dominant rational self-map f: X → X, and any point x with a well-defined forward orbit, if the orbit O_f(x) is Zariski dense in X then the orbit is generic in the sense that for every proper subvariety Y of X the set {n ≥ 0 | f^n(x) ∈ Y} is finite.

Background

The conjecture asserts a strong sparsity property of orbit intersections with proper subvarieties once the orbit is Zariski dense. It is a far-reaching analogue of classical Mordell–Lang phenomena in an arithmetic–dynamical setting.

In this paper the conjecture is used as a conditional ingredient relating arithmetic and dynamical degrees: prior results verify the Kawaguchi–Silverman conjecture under this dynamical Mordell–Lang assumption for certain cohomologically hyperbolic maps. The general statement of the dynamical Mordell–Lang conjecture remains open.

References

The Dynamical Mordell-Lang conjecture proposed by Ghioca and Tucker asserts that for every $x\in X_{f}(\overline{})$, if $O_f(x)$ is Zariski dense, then the $f$-orbit of $x$ is generic c.f. (see also Conjecture 1.2).

— Algebraic dynamics and recursive inequalities  (2402.12678 - Xie, 2024) in Subsection “Kawaguchi-Silverman conjecture”, discussion of related conjectures

Therefore, in order to prove the DML(1) property for regular endomorphisms, our result solves the $\mathbb{G}_m$-case and leaves the $\mathbb{A}1$-case open.

— On the DML(1) property for regular endomorphisms of affine spaces: the $\mathbb{G}_m$-case  (2609.29107 - Yang et al., 24 Sep 2026) in Introduction, immediately after Theorem 1 (the theorem labeled \ref{mainthm})

When we were typing this manuscript, A.I. claimed that it can strengthen Theorem \ref{mainthm} by changing the phrase strictly less than $d$" intonot greater than $d$." If so, then this gives a (maybe) new proof of the DML conjecture for regular endomorphisms of $\mathbb{A}2$. After comprehending the arguments in this article, the reader may realize that the remaining component is exactly ``the DML conjecture for regular endomorphisms of projective surfaces". We will try to comprehend and arrange its proof for this result later.

— On the DML(1) property for regular endomorphisms of affine spaces: multiplicities of points at infinity  (2610.05850 - Yang et al., 5 Oct 2026) in Remark 1(ii), Section 1