Sh:822
- Börner, F., Goldstern, M., & Shelah, S. (2023). Automorphisms and strongly invariant relations. Algebra Universalis, 84(4), Paper No. 27, 23. arXiv: math/0309165 DOI: 10.1007/s00012-023-00818-4 MR: 4629461
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Abstract:
We investigate characterizations of the Galois connection {\rm sInv}–{\rm 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 arbitrary intersections, but is not closed under {\rm sInv}{\rm 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.
- Version 2023-04-23_2 (21p)
Bib entry
@article{Sh:822,
author = {B{\"o}rner, Ferdinand and Goldstern, Martin and Shelah, Saharon},
title = {{Automorphisms and strongly invariant relations}},
journal = {Algebra Universalis},
fjournal = {Algebra Universalis},
volume = {84},
number = {4},
year = {2023},
pages = {Paper No. 27, 23},
issn = {0002-5240},
mrnumber = {4629461},
mrclass = {03C50 (03C10 06A15)},
doi = {10.1007/s00012-023-00818-4},
note = {\href{https://arxiv.org/abs/math/0309165}{arXiv: math/0309165}},
arxiv_number = {math/0309165}
}