arXiv:1803.09306v4

Simultaneous Diophantine approximation: sums of squares and homogeneous polynomials

Dmitry Kleinbock, Nikolay Moshchevitin

math.NTmath.DS11J1311J54

Abstract

Let ff be a homogeneous polynomial with rational coefficients in dd variables. We prove several results concerning uniform simultaneous approximation to points on the graph of ff, as well as on the hypersurface {f(x1,,xd)=1}\{f(x_1,\dots,x_d) = 1\}. The results are first stated for the case f(x1,,xd)=x12++xd2,f(x_1,\dots,x_d) = x_1^2+\dots+x_d^2, which is of particular interest.

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Audited against arXiv v4

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.

Current report

Detailed mathematical audit

Generated August 19, 2026
01Statements2 reported findingsCorrect

The sharp Dirichlet-type bounds for simultaneous approximation subject to sums-of-squares constraints, including the general quadratic-form variants, are correct.

Theorems 2.1 and 2.2Correct

Simultaneous approximation with sums of squares

Section 2 · Theorems 2.1–2.2 · arXiv:1803.09306v4

The simplex lemma confines rational approximants of bounded height to a rational hyperplane. Combined with the transference inequalities for uniform exponents, the case analysis gives the asserted approximation exponent and shows sharpness in the stated dimension ranges.

Full paper, version 4
Theorem 3.1 and statements 1a–3aCorrect

Quadratic-form generalizations

Section 3 and Sections 7–9 · Theorem 3.1 and statements 1a–3a · arXiv:1803.09306v4

Diagonalization and rational parametrization reduce each nonsingular quadratic constraint to the same lattice-exponent problem. The signature and isotropic-rank cases treated in Sections 7–9 exhaust the hypotheses and give the displayed bounds.

02Proofs2 reported findingsCorrect

The simplex lemma, transference step, and quadratic-form case analysis are correct and complete.

Sections 4–6Correct and complete

Simplex and transference estimates have compatible constants

Sections 4–6 · arXiv:1803.09306v4

The determinant lower bound for distinct rational points contradicts the upper bound supplied by a small approximation ball unless the points lie on one rational hyperplane. The Marnat–Moshchevitin transference inequality then converts the resulting dual obstruction to the claimed simultaneous exponent with the stated endpoints.

Sections 7–9Correct and complete

All quadratic signatures are covered

Sections 7–9 · arXiv:1803.09306v4

The proof separates anisotropic, split, and intermediate-rank forms. In each case the rational linear change of coordinates preserves exponents up to fixed constants, and the parametrization or hyperplane argument supplies both the upper and lower bounds required by the corresponding statement.

03Novelty0 reported findingsNo non-novelty findings

No non-novelty findings.

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Paper
arXiv:1803.09306v4
Authors listed
Dmitry Kleinbock, Nikolay Moshchevitin
Audit date
August 19, 2026
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