English

Quadratic forms representing all odd positive integers

Number Theory 2018-01-22 v2

Abstract

We consider the problem of classifying all positive-definite integer-valued quadratic forms that represent all positive odd integers. Kaplansky considered this problem for ternary forms, giving a list of 23 candidates, and proving that 19 of those represent all positive odds. (Jagy later dealt with a 20th candidate.) Assuming that the remaining three forms represent all positive odds, we prove that an arbitrary, positive-definite quadratic form represents all positive odds if and only if it represents the odd numbers from 1 up to 451. This result is analogous to Bhargava and Hanke's celebrated 290-theorem. In addition, we prove that these three remaining ternaries represent all positive odd integers, assuming the generalized Riemann hypothesis. This result is made possible by a new analytic method for bounding the cusp constants of integer-valued quaternary quadratic forms QQ with fundamental discriminant. This method is based on the analytic properties of Rankin-Selberg LL-functions, and we use it to prove that if QQ is a quaternary form with fundamental discriminant, the largest locally represented integer nn for which Q(x)=nQ(\vec{x}) = n has no integer solutions is O(D2+ϵ)O(D^{2 + \epsilon}).

Keywords

Cite

@article{arxiv.1111.0979,
  title  = {Quadratic forms representing all odd positive integers},
  author = {Jeremy Rouse},
  journal= {arXiv preprint arXiv:1111.0979},
  year   = {2018}
}

Comments

51 pages, improvements were made to the Petersson inner product bounds

R2 v1 2026-06-21T19:30:43.311Z