Skip to main content
11 events
when toggle format what by license comment
Aug 7, 2016 at 20:45 history edited Turbo
edited tags
Mar 14, 2013 at 1:35 answer added rzach timeline score: 6
Feb 26, 2013 at 19:55 vote accept Samuel Reid
Feb 22, 2013 at 2:35 comment added Noah Schweber I believe the book "Toposes and local set theories" treats this to some extent, in chapter 6; I think Maclane/Moerdijk also goes into this, albeit at a much higher level of abstraction.
Feb 6, 2013 at 17:16 comment added Samuel Reid @Peter LeFanu Lumsdaine: Your comment is very interesting to me and I can't find many references on the topic you alluded to. Have you thought of anything I could look up regarding this? Possibly a survey article, or at least a journal article which defines the words you are using in the context of modal logic? Thanks
Feb 4, 2013 at 18:59 comment added Rob Myers The answers below have mentioned that not every first order definable class of graphs is definable by a formula of propositional modal logic. It might be worth mentioning that first order logic is the smallest extension of modal logic endowed with nominals (variables whose semantics is a singleton) and the universal modality (allowing one to assert truth at every state) that has interpolation. Also, modal logic with nominals and the universal modality is decidable. See Balder Ten Cate's thesis hylo.loria.fr/content/papers/files/phd-thesis.pdf.
Feb 3, 2013 at 22:00 answer added user30304 timeline score: 5
Feb 3, 2013 at 21:10 answer added Joel David Hamkins timeline score: 11
Feb 3, 2013 at 20:19 answer added Noah Schweber timeline score: 16
Feb 3, 2013 at 19:28 comment added Peter LeFanu Lumsdaine One category-theoretic approach to this is that Kripke models of modal logic can be seen as sheaf/presheaf models, with the modalities often coming from sheafification for some Grothendieck coverage (equivalently, some Lawvere-Tierney closure operator). I can’t off the top of my head remember where is a good source for reading up on this, but hopefully those keywords should at least be useful for searching with.
Feb 3, 2013 at 18:26 history asked Samuel Reid CC BY-SA 3.0