English

On additive complements in the complement of a set of natural numbers

Number Theory 2026-01-14 v1

Abstract

Let AA be a set of natural numbers. A set BB, a set of natural numbers, is an additive complement of the set AA if all sufficiently large natural numbers can be represented in the form x+yx+y, where xAx\in A and yBy\in B. Erd\H{o}s proposed a conjecture that every infinite set of natural numbers has a sparse additive complement, and in 1954, Lorentz proved this conjecture. This article describes the existence or non-existence of those additive complements of the set AA that is a subset of the complement of AA. We provide a ratio test to verify the existence of such additive complements. In precise, we prove that if A={ai:iN}A=\{a_i: i\in \mathbb{N}\} is a set of natural numbers such that ai<ai+1a_i<a_{i+1} for iNi \in \mathbb{N} and lim infn(an+1/an)>1\liminf_{n\rightarrow \infty } (a_{n+1}/a_{n})>1, then there exists a set BNAB\subset \mathbb{N}\setminus A such that BB is a sparse additive complement of the set AA.

Keywords

Cite

@article{arxiv.2410.22664,
  title  = {On additive complements in the complement of a set of natural numbers},
  author = {Bhuwanesh Rao Patil and Mohan},
  journal= {arXiv preprint arXiv:2410.22664},
  year   = {2026}
}

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11 pages