English

The universal zero-sum invariant and weighted zero-sum for infinite abelian groups II

Combinatorics 2026-07-02 v1 Number Theory

Abstract

Let GG be an abelian group, and let F(G)\mathcal F (G) be the free commutative monoid with basis GG, and A(G)\mathcal A (G) the set consisting of all minimal zero-sum subsequences over GG. For any subset ΩF(G)\Omega \subset \mathcal F (G), we define the universal zero-sum invariant dΩ(G){\mathsf d}_{\Omega}(G) as the minimal positive integer \ell such that every sequence TT over GG of length \ell contains a subsequence lying in Ω\Omega. The classical Davenport constant D(G){\rm D}(G) for GG can also be written as dA(G)(G){\mathsf d}_{\mathcal A (G)}(G). We give a complete classification of all finite abelian groups for which A(G)\mathcal A(G) is a minimal set to represent the Davenport constant. We also investigate the weighted Davenport constant over abelian groups (which may be infinite). Let FF and GG be abelian groups, and let ΨHom(F,G)\Psi \subseteq \mathrm{Hom}(F,G) denote a weight set. We reinterpret the weighted Davenport constant DΨ(G)D_{\Psi}(G) in terms of coverings of Cartesian powers FnF^n by kernels of induced homomorphisms arising from tuples in Ψn\Psi^n; these homomorphisms are naturally linked to coproducts in the category of abelian groups. This motivates the notion of kernel-cover compactness, a property characterizing when such kernel coverings admit finite subcovers. We establish a correspondence between weighted zero-sum invariants and kernel-cover structures, where the bound DΨ(G)nD_{\Psi}(G)\le n is equivalent to a canonical kernel-cover property on FnF^n. We further study finite reduction phenomena for infinite weight sets and provide sufficient conditions ensuring uniform kernel-cover compactness. The present work constitutes a follow-up to [G. Wang, Comm. Algebra, 2025].

Keywords

Cite

@article{arxiv.2607.02132,
  title  = {The universal zero-sum invariant and weighted zero-sum for infinite abelian groups II},
  author = {Guoqing Wang},
  journal= {arXiv preprint arXiv:2607.02132},
  year   = {2026}
}

Comments

17 pages