English

Comparison estimates for linear forms in additive number theory

Number Theory 2021-01-06 v4

Abstract

Let RR be a commutative ring RR with 1R1_R and with group of units R×R^{\times}. Let Φ=Φ(t1,,th)=i=1hφiti\Phi = \Phi(t_1,\ldots, t_h) = \sum_{i=1}^h \varphi_it_i be an hh-ary linear form with nonzero coefficients φ1,,φhR\varphi_1,\ldots, \varphi_h \in R. Let MM be an RR-module. For every subset AA of MM, the image of AA under Φ\Phi is Φ(A)={Φ(a1,,ah):(a1,,ah)Ah}. \Phi(A) = \{ \Phi(a_1,\ldots, a_h) : (a_1,\ldots, a_h) \in A^h \}. For every subset II of {1,2,,h}\{1,2,\ldots, h\}, there is the subset sum sI=iIφi. s_I = \sum_{i\in I} \varphi_i. Let S(Φ)={sI:I{1,2,,h}}. \mathcal{S} (\Phi) = \{s_I: \emptyset \neq I \subseteq \{1,2,\ldots, h\} \}. Theorem. Let Υ(t1,,tg)=i=1gυiti\Upsilon(t_1,\ldots, t_g) = \sum_{i=1}^g \upsilon_it_i and Φ(t1,,th)=i=1hφiti\Phi(t_1,\ldots, t_h) = \sum_{i=1}^h \varphi_it_i be linear forms with nonzero coefficients in the ring RR. If {0,1}S(Υ)\{0, 1\} \subseteq \mathcal{S} (\Upsilon) and S(Φ)R×\mathcal{S} (\Phi) \subseteq R^{\times}, then for every ε>0\varepsilon > 0 and c>1c > 1 there exist a finite RR-module MM with M>c|M| > c and a subset AA of MM such that Υ(A{0})=M\Upsilon(A \cup \{0\}) = M and Φ(A)<εM|\Phi(A)| < \varepsilon |M|.

Keywords

Cite

@article{arxiv.1604.08940,
  title  = {Comparison estimates for linear forms in additive number theory},
  author = {Melvyn B. Nathanson},
  journal= {arXiv preprint arXiv:1604.08940},
  year   = {2021}
}

Comments

20 pages. Minor revisions

R2 v1 2026-06-22T13:44:56.868Z