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Naïm Favier (May 12 2024 at 09:01):I remember seeing a paper or book that was an introduction to presheaves or sheaves or maybe topos theory or maybe category theory in general, that spent a lot of time dwelling on examples of presheaves on various categories, with lots of diagrams: in particular it was showing both the representation of graphs as presheaves over ∙⇉∙ (so that points and arrows are both elements of the presheaf) and the representation of an ℕ-set (where ℕ is seen as a one-object category) as a bunch of points and arrows showing the transitions corresponding to the generating map.
Now I can't find it and it's driving me crazy. Does anybody know what I'm talking about?
Ralph Sarkis (May 12 2024 at 09:58): Naïm Favier (May 12 2024 at 10:09):Yes!! TYVM
Todd Trimble (May 17 2024 at 21:44):The title of this thread made me smile. Probably everyone knows the sly reference, but in case not, have a listen to Evgeny Kissin (and you'll probably then say, oh yeah, I've heard that before!).