How to prove equations using diagrams, part 1

(epatters.org)

78 points | by frostbyte7 2 days ago ago

8 comments

  • henearkr a day ago ago

    Very interesting!!

    A nitpick, for a J-shaped diagram D, J is the "index category" or the "scheme" of D, not the "shape" like written in the article.

    • epatters a day ago ago

      Thanks!

      Yes, there are lots of different names for the domain of a diagram, but "shape" is a common enough one. You can find it in standard sources, including the nLab [1] and some textbooks.

      [1] <https://ncatlab.org/nlab/show/diagram>

      • henearkr a day ago ago

        Ah you're right!

        My bad for not keeping up.

    • JadeNB a day ago ago

      The article does mention "index[ing] category." I think terminology here is not especially universal: I am a mathematician but not a category theorist, and I have seen "shape" but not "scheme."

      • henearkr a day ago ago

        Yes, it is completely understandable with "shape".

        As I am not a professional mathematician, I have read a very limited number of books touching the subject, so my vocabulary was in fact a bit too narrow. I should have looked up on nLab before making a fool of myself.

        • JadeNB a day ago ago

          Don't be hard on yourself. It was a perfectly reasonable and polite comment.

  • boldslogan a day ago ago

    man ive recently stumbled on this concept of functor or nonsymbolic logic and such. don't suppose you have any suggestions to look at?

  • fn-mote a day ago ago

    This is a category theory post. The subtitle is “initial functors”.

    Now you can save yourself a click.