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2101.08417

ZARISKI DENSITY OF POINTS WITH MAXIMAL ARITHMETIC DEGREE FOR SURFACES

KAORU SANO, TAKAHIRO SHIBATA

correctmedium confidence
Category
Not specified
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:55 AM

Audit review

The paper proves that for a smooth projective surface X/K with potentially dense rational points and any surjective self-morphism f with δ_f>1, the property (DR) holds (Definition 1.3 and Theorem 1.5), via reduction to minimal models and a case-by-case geometric analysis (K3/Enriques/abelian/elliptic surface cases) using Lemmas 3.2–3.3 and Proposition 4.5, together with elliptic-fibration inputs (Lemmas 3.5–3.6) . The model’s solution gives a different (height-theoretic) route: construct nef eigenclasses and canonical heights, use a dense set of points with α_f(x)=δ_f, and then enforce pairwise disjoint orbits by normalizing canonical heights. This approach is essentially correct but needs one auxiliary justification: that among a Zariski-dense set of points with α_f(x)=δ_f, the normalized canonical heights take infinitely many distinct values. This can be supplied using Northcott on curves where the eigen-divisor restricts to an ample class and the finiteness of f-periodic curves on surfaces where needed. With that small patch, both the paper’s argument and the model’s argument are correct, though they are substantially different in technique.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The paper establishes a natural strengthening of prior results by proving the (DR) property for all smooth projective surfaces with δ\_f>1 and potentially dense rational points. The argument is well structured—via birational/finite invariances and a careful case analysis (K3/Enriques/abelian and elliptic surfaces)—and leverages a geometric criterion ensuring disjoint orbits. Minor clarifications (notational and expository) would improve readability; mathematically the work appears sound.