De Morgan classifying toposes
Category Theory
2013-04-26 v1 Logic
Abstract
We present a general method for deciding whether a Grothendieck topos satisfies De Morgan's law (resp. the law of excluded middle) or not; applications to the theory of classifying toposes follow. Specifically, we obtain a syntactic characterization of the class of geometric theories whose classifying toposes satisfy De Morgan's law (resp. are Boolean), as well as model-theoretic criteria for theories whose classifying toposes arise as localizations of a given presheaf topos.
Cite
@article{arxiv.0808.1519,
title = {De Morgan classifying toposes},
author = {Olivia Caramello},
journal= {arXiv preprint arXiv:0808.1519},
year = {2013}
}
Comments
37 pages