arXiv:2607.19952v1

The Pila-Zannier strategy for Drinfeld modules and Drinfeld modular curves

Gal Binyamini, Dmitry Novikov, Francesco Maria Saettone

math.NTmath.AG11G0911J9314G05

Abstract

We extend the Pila-Zannier strategy to Drinfeld modules: we prove analogues of the Manin-Mumford theorem for a product of two Drinfeld modules of equal rank, and of the André-Oort theorem for a product of two Drinfeld modular curves. In characteristic zero, several steps of this strategy rest on oo-minimality, which has no counterpart over a function field; we replace the counting step by the rigid analytic Pila-Wilkie theorem of Binyamini-Kato, and this appears to be its first arithmetic application. The functional transcendence input, namely an analogue of the Ax-Lindemann theorem in both settings, is established here by an independent point counting argument.

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Audited against arXiv v1

Not a correctness certificate. A “Correct” result may include yellow typos or minor formal corrections that do not affect substantive soundness. It means this audit found no unresolved substantive error under the stated criteria; it does not replace expert scrutiny or formal verification.

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Detailed mathematical audit

Generated August 15, 2026
01Statements3 reported findingsContains unsupported statements

The two Ax-Lindemann conclusions and the Andre-Oort conclusion are supported, the latter after the explicit repair to the cusp cover recorded below. The stated Manin-Mumford theorem for arbitrary Drinfeld modules over CC_\infty is not verified by the paper's proof: the preliminary specialization preserves each fixed torsion group scheme but does not preserve a Zariski-dense set of torsion points or lift specialness from the selected fiber. No counterexample to that theorem was found.

Theorem A · Drinfeld-module case (Theorem 3.23)Not able to verify

Manin-Mumford over arbitrary CC_\infty coefficients

Pages 2 and 31-33 · Section 3.3.1 and Theorem 3.23 · arXiv:2607.19952v1

The counting argument is carried out only after replacing the given modules and curve by a specialization over a finite extension of FF. The preceding paragraph proves that, for each fixed nonzero aa, the finite etale group scheme of aa-torsion keeps its cardinality in a suitable generic-characteristic fiber. It does not prove that one closed fiber preserves infinitely many torsion incidences on VV, that their images remain Zariski dense, or that a torsion-translate conclusion for the fiber lifts to the original curve. These are exactly the implications needed for the sentence 'we may assume' in the proof. The paper notes that the conclusion is within reach of prior Manin-Mumford work, but it also notes a difference for products of distinct modules; no cited theorem is matched here to the full printed scope. The appropriate verdict is therefore inability to verify, not falsity.

Full paper, version 1
Theorem A · hyperbolic case (Theorem 3.24)Correct

Andre-Oort for a product of Drinfeld modular curves when qq is odd

Pages 2 and 34-39 · Theorem 3.24 · arXiv:2607.19952v1

The printed pigeonhole estimate uses the unnecessarily large center sets from Lemma 2.4 and therefore does not itself force a block. The lemma's construction admits a direct sharper version: for z=a+bΔz=a+b\sqrt{\Delta} with ziR|z|_i\le R, the polynomial part P2P_2 has degree at most d=logqRd=\lceil\log_q R\rceil, while bRΔ1/2|b|\le R|\Delta|^{-1/2} implies that the truncated numerator P1P_1 in P1/TcP_1/T^c also has degree at most dd. Thus only q2d+2=RO(1)q^{2d+2}=R^{O(1)} centers are needed, independently of the field discriminant. Substituting these sets in (3.12) makes their total cost DO(ε)D^{O(\varepsilon)}, so the class-number lower bound D1/2εD^{1/2-\varepsilon} contradicts the rigid counting upper bound for sufficiently small exponents. The remaining height, local-uniformization, block-counting, and Ax-Lindemann steps then establish the stated conclusion.

Full paper, version 1
Theorem B (Theorems 3.1 and 3.11)Correct

Ax-Lindemann in the linear and hyperbolic settings

Pages 2 and 19-28 · Sections 3.1 and 3.2 · arXiv:2607.19952v1

The lattice-counting and additive-polynomial argument in the Drinfeld exponential setting yields a weakly special image, and the stabilizer argument in the jj-uniformization setting reduces the correspondence to an ordinary PGL2(F)PGL_2(F) conjugation after excluding a Frobenius twist by growth in the unipotent subgroup. No incorrect or unsupported central step was found in these two proofs. The harmless orientation convention for a negative Frobenius exponent can be handled by interchanging the two coordinates and requires no change to the result.

02Proofs3 reported findingsContains incorrect or incomplete proofs

The proof of the Drinfeld-module Manin-Mumford case has an unresolved specialization gap. The Andre-Oort proof uses a cusp cover whose printed cardinality is too large for the claimed pigeonhole contradiction, but the construction itself gives a sharper cover that repairs the proof. No further central proof defect meeting the audit's evidence threshold was found.

Section 3.3.1Incomplete as written

Specialization does not transfer the dense torsion problem

Page 31 · paragraph before and first paragraph of Theorem 3.23's proof · arXiv:2607.19952v1

After spreading out the coefficients, the text chooses one closed point and observes that every fixed aa-torsion scheme remains finite etale of the expected size. It then immediately assumes that the original modules and VV are defined over the residue field. This does not follow: preserving a finite group scheme one level at a time neither supplies one fiber carrying a dense collection of the original varying-order torsion points nor proves that specialness detected after specialization lifts to the generic/original fiber. A repair needs a genuine specialization theorem for the pair (V,D×D)(V,D\times D') or a separate descent argument covering the full CC_\infty case.

Full paper, version 1
Lemma 2.4 and Equation (3.12)Incorrect as written · verified repair

The printed cusp-cover count cannot yield the asserted contradiction

Pages 10 and 35-39 · Lemma 2.4 and proof of Theorem 3.24 · arXiv:2607.19952v1

Lemma 2.4 defines d=d+cd'=d+c, with c=degT(Δ)/2c=\lceil\deg_T(\Delta)/2\rceil, and its displayed center set has cardinality q2d+2q^{2d'+2}. The proof of Theorem 3.24 divides the Galois orbit by the product of two such cardinalities and then says that the result contradicts an HηH^\eta block count. That inference is invalid: the two cover costs include discriminant factors of roughly Δ1Δ2|\Delta_1||\Delta_2| and can dominate the available D1/2εD^{1/2-\varepsilon} orbit lower bound. The repair is internal to Lemma 2.4. Its estimates give degP2d\deg P_2\le d and, from bRΔ1/2|b|\le R|\Delta|^{-1/2}, degP1d\deg P_1\le d as well. Restricting both numerators to degree at most dd preserves the cover and reduces it to q2d+2q^{2d+2}. With this corrected cardinality, (3.12) has size D1/2O(ε)D^{1/2-O(\varepsilon)} and the block-counting contradiction follows.

Full paper, version 1
Remaining proof chainCorrect and complete after the stated repair

Functional-transcendence and counting inputs

Pages 7-30 and 31-39 · Sections 2 and 3 · arXiv:2607.19952v1

Apart from the two issues isolated above, the torsion-height estimates, quadratic-point height bounds, rigid block-counting applications, algebraic-block extraction, and both Ax-Lindemann arguments are coherently matched to their uses. The small omission of first passing to a finite extension with stable reduction before applying Proposition 2.8 is a direct extension-invariance step and does not warrant a separate adverse finding under the prompt's mandatory gate.

03Novelty0 reported findingsNo non-novelty findings

No non-novelty findings.

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Paper
arXiv:2607.19952v1
Authors listed
Gal Binyamini, Dmitry Novikov, Francesco Maria Saettone
Audit date
August 15, 2026
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