Automorphisms and strongly invariant relations
Logic
2007-05-23 v1 Rings and Algebras
Abstract
We investigate characterizations of the Galois connection sInv-Aut between sets of finitary relations on a base set A and their automorphisms. In particular, for A=omega_1, we construct a countable set R of relations that is closed under all invariant operations on relations and under arbitray intersections, but is not closed under sInv(Aut(-)). Our structure (A,R) has an omega-categorical first order theory. A higher order definable well-order makes it rigid, but any reduct to a finite language is homogeneous.
Cite
@article{arxiv.math/0309165,
title = {Automorphisms and strongly invariant relations},
author = {Ferdinand Börner and Martin Goldstern and Saharon Shelah},
journal= {arXiv preprint arXiv:math/0309165},
year = {2007}
}
Comments
16 pages, LaTeX2e with eepic macros