Back to Search Start Over

Generic countably infinite groups

Authors :
Elekes, Márton
Gehér, Boglárka
Kanalas, Kristóf
Kátay, Tamás
Keleti, Tamás
Publication Year :
2021

Abstract

Countably infinite groups (with a fixed underlying set) constitute a Polish space $G$ with a suitable metric, hence the Baire category theorem holds in $G$. We study isomorphism invariant subsets of $G$, which we call group properties. We say that the generic countably infinite group is of property $P$ if $P$ is comeager in $G$. We prove that every group property with the Baire property is either meager or comeager. We show that there is a comeager elementary equivalence class in $G$ but every isomorphism class is meager. We prove that the generic group is algebraically closed, simple, not finitely generated and not locally finite. We show that in the subspace of Abelian groups the generic group is isomorphic to the unique countable, divisible torsion group that contains every finite Abelian group. We sketch the model-theoretic setting in which many of our results can be generalized. We briefly discuss a connection with infinite games.<br />Comment: We have very recently become aware of the fact that another research group is working on very similar problems, see arXiv:2006.14048

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2110.15902
Document Type :
Working Paper