English

Representations of finite number of quadratic forms with same rank

Number Theory 2020-01-01 v1

Abstract

Let m,nm, n be positive integers with mnm\le n. Let κ(m,n)\kappa(m,n) be the largest integer kk such that for any (positive definite and integral) quadratic forms f1,,fkf_1,\ldots,f_k of rank mm, there exists a quadratic form of rank nn that represents fif_i for any ii with 1ik1\le i \le k. In this article, we determine the number κ(m,n)\kappa(m,n) for any integer mm with 1m81\le m\le 8, except for the cases when (m,n)=(3,5)(m,n)=(3,5) and (4,6)(4,6). In the exceptional cases, it will be proved that 1κ(3,5), κ(4,6)21\le \kappa(3,5), \ \kappa(4,6)\le 2. We also discuss some related topics.

Cite

@article{arxiv.1912.12930,
  title  = {Representations of finite number of quadratic forms with same rank},
  author = {Daejun Kim and Byeong-Kweon Oh},
  journal= {arXiv preprint arXiv:1912.12930},
  year   = {2020}
}

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13 pages