English

Homological dimension and dimensional full-valuedness

Geometric Topology 2017-01-10 v2 General Topology

Abstract

There are different definitions of homological dimension of metric compacta involving either \v{C}ech homology or exact (Steenrod) homology. In this paper we investigate the relation between these homological dimensions with respect to different groups. It is shown that all homological dimensions of a metric compactum X with respect to any field coincide provided X is homologically locally connected with respect to the singular homology up to dimension n=dim X. We also prove that any two-dimensional lc^2 metric compactum X satisfies the equality dim(X times Y)=dim X+dim Y for any metric compactum Y. This improves the well known result of Kodama that every two-dimensional ANR is dimensionally full-valued. Actually, the condition X to be lc^2 can be weaken to the existence at every point x a neighborhood V of x such that the inclusion homomorphism H_k(V;S^1)\to H_k(X;S^1)$ is trivial for all k=1,2.

Keywords

Cite

@article{arxiv.1611.08347,
  title  = {Homological dimension and dimensional full-valuedness},
  author = {Vesko Valov},
  journal= {arXiv preprint arXiv:1611.08347},
  year   = {2017}
}

Comments

10 pages

R2 v1 2026-06-22T17:03:54.810Z