245 pointsby PaulHoule7 days ago8 comments
  • dwlg007 days ago
    Braid groups are really interesting, and they also come up in fluid mixing: https://people.math.wisc.edu/~thiffeault/talks/gordon2022.pd...
    • tucnak6 days ago
      The slides are a blast, thanks

      Classic mathematicians!

  • bregma7 days ago
    Back in the 1980s I was taking a foundational computer science course in which we derived Goedel's result using Cantor diagonalization. Excellent course. We were watching the TV version of Hitchhiker's Guide to the Galaxy at the time, too. One day I had the realization that since any recursively enumerable function could be interpreted as a computer program (given the right interpreter), that the sweater I was wearing was in fact possibly a computer program, and that all knitting (and some crocheting) was in fact just a manifestation of code in another language.

    I then went on to realize any enumerable set could be similarly interpreted, including the entire countable population of Earth. And we already had the answer (42), but what was the question?

    • gwern7 days ago
      I suppose if nothing else, you could encode Wang tiles (https://en.wikipedia.org/wiki/Wang_tile) into knitting and then that's Turing-complete? Or would there be some better CA to encode?
    • internet_rand07 days ago
      sorry, 42 is not gonna take us much farther

      42 is a stand in for 41 and 43 which are some twin prime

      for me to further elaborate on this crazy idea that haunts me (I must admit I also haunt these ideas) requires a twin prime theorem which we are still waiting for in 2025....

  • statusfailed6 days ago
    I've been hoping for a nice concrete example of braided monoidal categories for ages, who knew that the best one was string diagrams that represent actual string! Great post!

    @the author - I assume you're aware that morphisms in symmetric monoidal categories can be represented using cospans of hypergraphs - do you know if there's a similar combinatorial representation for braided monoidal categories?

  • Y_Y7 days ago
    Does anyone know a good emulator for knitting machines? I'd love to play with these programs, but I'd like to get some practice before I start messing with real wool.
    • camblomquist7 days ago
      Someone else mentioned the acrylic, I'm going to mention Scarlett Sparks' Open Source Knitting Machine if part of the fear is actually investing in the machine https://github.com/ScarlettSparks/KnittingMachine
    • MikeTheGreat7 days ago
      Possibly off-topic, but if you're looking to reduce your costs you should look at acrylic yarn. There's also cotton yarn if you're looking for something less scratchy :)
  • t-trash6 days ago
    Reminds me of the work in the Carnegie Melon Textile Lab on the semantics and scheduling for knitting machine compilers (https://textiles-lab.github.io/publications/2023-knitout-sem...)
    • nolamark6 days ago
      "This work is in part a collaboration with folks currently and previously at CMU, including Jenny Lin, Tom Price, Jim McCann, and Hannah Fechtner."
  • WillAdams7 days ago
    Still kicking myself for not buying a "3D Knitted Chisel Roll" back when Lee Valley had them --- last I checked it might have been possible to import one from Europe, but having a hard time justifying that.....
  • kappasan7 days ago
    Speaking of computational knitting, I recently learned about "solid knitting" [1] which is awesome.

    https://www.cs.cmu.edu/news/2024/solid-knitting

  • ruined7 days ago
    the formalization of textile programming really brings computer science full-circle. as a neoluddite i approve
    • speerer7 days ago
      ...as demonstrated by the analogy in the original post here, where he explains the concrete concept of knitting stitches by reference to the much more abstract concept of garbage collection in computer programming!
    • 7 days ago
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