Additive Bases in Abelian Groups

TL;DR

This paper proves that unions of sufficiently many generating subsets in finite abelian groups form additive bases, advancing the additive bases conjecture, and explores related bounds and geometric reformulations.

Contribution

It generalizes previous results by establishing conditions under which unions of generating subsets form additive bases in finite abelian groups.

Findings

Union of >2m log log |G| generating subsets forms an additive basis.

Provides lower bounds for sumset values in vector spaces.

Links the additive bases conjecture to lattice covering problems.

Abstract

Let $G$ be a finite, non-trivial abelian group of exponent $m$, and suppose that $B_1, ..., B_k$ are generating subsets of $G$. We prove that if $k>2m \ln \log_2 |G|$, then the multiset union $B_1\cup...\cup B_k$ forms an additive basis of $G$; that is, for every $g\in G$ there exist $A_1\subset B_1, ..., A_k\subset B_k$ such that $g=\sum_{i=1}^k\sum_{a\in A_i} a$. This generalizes a result of Alon, Linial, and Meshulam on the additive bases conjecture. As another step towards proving the conjecture, in the case where $B_1, ..., B_k$ are finite subsets of a vector space we obtain lower-bound estimates for the number of distinct values, attained by the sums of the form $\sum_{i=1}^k \sum_{a\in A_i} a$, where $A_i$ vary over all subsets of $B_i$ for each $i=1, >..., k$. Finally, we establish a surprising relation between the additive bases conjecture and the problem of covering the vertices of a unit cube by translates of a lattice, and present a reformulation of (the strong form of) the conjecture in terms of coverings.