arXiv:2211.07474v2
Abstract
In this paper, we obtain global function field versions of the results of Schinzel-Postnikova for multiplicative groups, and of Hahn-Cheon for elliptic curves, which is an analog of the former result.
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Detailed mathematical audit
01Statements2 reported findingsCorrect
The primitive-order results for elliptic curves and one-dimensional tori over global function fields are correct. Two central proofs contain genuine written defects, but both admit direct verified repairs without changing the theorem statements.
Prescribed reduction orders on elliptic curves
Pages 3–7 · Theorems 3.1 and 3.4 · arXiv:2211.07474v2
For integers prime to the characteristic, local formal-group heights outside a fixed finite set are unchanged under multiplication by divisors of . If is a bad index with no reduction of exact order , this bounds by a sum of heights of over prime divisors of , plus negligible contributions at the fixed places. Quadraticity of the canonical height and then bound every bad index, proving Theorem 3.1. For an ordinary curve, adjoining a point of order and applying Theorem 3.1 to forces the prime-to- and -primary parts of the reduction order of to be exactly and , respectively.
Full paper, version 2 ↗Prescribed reduction orders on one-dimensional tori
Pages 7–9 · Proposition 4.1 and Theorem 4.2 · arXiv:2211.07474v2
For , Möbius inversion of the valuations of shows that absence of a place where has exact order would make the divisor of consist only of the poles of , contradicting the product formula unless is constant. A one-dimensional torus becomes over a finite splitting field; after extending the isomorphism over rings of integers away from finitely many places, the natural residue-field injection preserves the exact reduction order. Proposition 4.1 over the splitting field therefore descends to the stated conclusion.
Full paper, version 2 ↗02Proofs4 reported findingsContains incorrect or incomplete proofs
The principal height and cyclotomic arguments are sound, but the proof of Theorem 3.1 starts with the wrong quantified contradiction hypothesis and the proof of Theorem 4.2 uses an invalid tensor product and lifting assertion. Each defect has a verified local repair that completes the intended proof. Several additional notation slips are typos.
The contradiction hypothesis has the wrong quantifier
Pages 4–5 · Proof of Theorem 3.1 · arXiv:2211.07474v2
The proof assumes that every sufficiently large is bad, meaning that no place gives exact order . This is stronger than the negation of the theorem and would only exclude eventual failure, not infinitely many isolated bad indices. The repair is to fix an arbitrary bad outside the finite preliminary range. Inequality (1) uses only the defining property of that single bad index, while the estimates at the finite set are uniform for all sufficiently large . The resulting comparison is which is impossible for all sufficiently large bad after choosing . Thus every bad index is bounded and the theorem follows. No statement change is needed.
Full paper, version 2 ↗The displayed base-change and arbitrary lifting argument is not defined
Pages 8–9 · Proof of Theorem 4.2 · arXiv:2211.07474v2
The formula is not defined because is not a -algebra, and an arbitrary -point need not be obtained by the asserted lift. The needed fact is simpler. After enlarging , the splitting isomorphism extends to the integral models over . For each the natural morphism base-changes the fixed point to , and the injection of residue fields identifies the reduction of with the base change of the reduction of . Exact order is preserved under that field extension. Proposition 4.1 applied to outside then proves the theorem exactly as stated.
Full paper, version 2 ↗The remaining elliptic-curve arguments are complete
Pages 3–7 · Lemmas 3.2–3.3 and proof of Theorem 3.4 · arXiv:2211.07474v2
For multiplication by an integer prime to , the linear term in the formal-group law is a unit, so the local parameter valuation and hence the local height are unchanged. Northcott finiteness makes , establishing the required local-height ratio. In Theorem 3.4, reduction preserves the order of the fixed torsion point outside finitely many places; elementary divisibility then forces both components of the order of to be exact.
Three unambiguous notation slips
Pages 7–9 · Proposition 4.1 and Theorem 4.2 · arXiv:2211.07474v2
In case 4 of Proposition 4.1 and its conclusion, the undefined set should be the previously defined set . In Theorem 4.2, should read . Earlier, the definition of says that “ has bad reduction”; the subject is . Each replacement is fixed uniquely by the surrounding definitions and changes no argument.
03Novelty0 reported findingsNo non-novelty findings
No non-novelty findings.