Definable Eilenberg--Mac Lane Universal Coefficient Theorems
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 , a (not necessarily compact) polyhedron , and an abelian Polish group 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 is the -dimensional definable homology group of with coefficients in and is the -dimensional definable cohomology group of with coefficients in . 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 -dual chain complex of Polish groups.
Cite
@article{arxiv.2009.10805,
title = {Definable Eilenberg--Mac Lane Universal Coefficient Theorems},
author = {Martino Lupini},
journal= {arXiv preprint arXiv:2009.10805},
year = {2020}
}