English

Definable Eilenberg--Mac Lane Universal Coefficient Theorems

Algebraic Topology 2020-10-13 v3 K-Theory and Homology Logic

Abstract

We prove definable versions of the Universal Coefficient Theorems of Eilenberg--Mac Lane expressing the (Steenrod) homology groups of a compact metrizable space in terms of its integral cohomology groups, and the (\v{C}ech) cohomology groups of a polyhedron in terms of its integral homology groups. Precisely, we show that, given a compact metrizable space XX, a (not necessarily compact) polyhedron YY, and an abelian Polish group GG with the division closure property, there are natural definable exact sequences \begin{equation*} 0\rightarrow \mathrm{Ext}\left( H^{n+1}(X),G\right) \rightarrow H_{n}(X;G)\rightarrow \mathrm{Hom}\left( H^{n}(X),G\right) \rightarrow 0 \end{equation*} and \begin{equation*} 0\rightarrow \mathrm{Ext}\left( H_{n-1}(Y),G\right) \rightarrow H^{n}(Y;G)\rightarrow \mathrm{Hom}\left( H_{n}(Y),G\right) \rightarrow 0 \end{equation*} which definably split, where Hn(X;G)H_{n}(X;G) is the nn-dimensional definable homology group of XX with coefficients in GG and Hn(Y;G)H^{n}(Y;G) is the nn -dimensional definable cohomology group of YY with coefficients in GG. Both of these results are obtained as corollaries of a general algebraic Universal Coefficient Theorem relating the cohomology of a cochain complex of countable free abelian groups to the definable homology of its GG-dual chain complex of Polish groups.

Keywords

Cite

@article{arxiv.2009.10805,
  title  = {Definable Eilenberg--Mac Lane Universal Coefficient Theorems},
  author = {Martino Lupini},
  journal= {arXiv preprint arXiv:2009.10805},
  year   = {2020}
}
R2 v1 2026-06-23T18:43:48.800Z