@themattsimpson @sarahdoingthing A category contains all the objects of a particular kind and all the functions between them.
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@St_Rev @themattsimpson it seems like the hard part is showing you're on the "same river" as before -
@St_Rev @themattsimpson (once you complete the portage) -
@sarahdoingthing @themattsimpson Well, going one way is frequently easy, lifting back to the original problem not so much. -
@sarahdoingthing Here's an example: the idea of 'invariants'. Say you have two colossally tangled masses of string, and you want to know... -
@sarahdoingthing ...if they're the 'same knot', topologically. This is super hard! But there are things called knot invariants. -
@sarahdoingthing A knot invariant is a recipe for turning a horribly complicated object (a tangled ball of string) into a simple one... -
@St_Rev (actually familiar from knitting tragedies)
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@St_Rev @themattsimpson@sarahdoingthing Oh, I see your analogy now! -
@Meaningness @themattsimpson@sarahdoingthing It's usually presented as this hybrid of syntactic logic and graph theory -
@Meaningness @themattsimpson@sarahdoingthing Really it's the Higher Knowledge, like Qabala--you need to know the main texts deeply first. -
@St_Rev My extremely vague recollection is that Rota taught it from Birkhoff’s book, or Birkoff’s notes, or something like that. -
@St_Rev I was only CS person in a graduate seminar. Rota gave me a good grade probably out of pity. -
@Meaningness Mac Lane, maybe? -
@St_Rev Pretty sure not. Was a long time ago, though, not absolutely sure. Can’t find it as a published book, suspect unpublished notes -
@St_Rev Rota and Birkhoff were buddies, though so I may be misremembering based on stories he told. - 8 more replies
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. Banned in Sweden. SubGenius, Zhuangist, white-hat troll. Defrocked mathematician. Brain problems.