Network Theory Seminar (Part 4)


Since I was in Banff, my student Franciscus Rebro took over this week and explained more about cospan categories. These are a tool for constructing categories where the morphisms are networks such as electrical circuit diagrams, signal flow diagrams, Markov processes and the like. For some more details see:

• John Baez and Brendan Fong, A compositional framework for passive linear networks.

Cospan categories are really best thought of as bicategories, and Franciscus gets into this aspect too.

10 Responses to Network Theory Seminar (Part 4)

  1. ashwin1729 says:

    Are all your Grad students left-handed?

    • John Baez says:

      I require them to learn how to write left-handed. If they can’t do that, they don’t have the mental flexibility to do well in category theory.

    • Jason Erbele says:

      I am a counterexample to the claim that all his grad students are left-handed. I think I somewhat make up for that defect with mirror writing and ambigraphs. And while I can write left-handed, it is not my preferred mode.

  2. arch1 says:

    I bought this until it hit me: Franciscus isn’t just writing left-handed. Nor is he just doing well in category theory. He’s doing *both at once*. I can only imagine the profligate mental energy expenditures required. Then I remembered that you, John, don’t *have* to speculate. You – notwithstanding all your professed AGW concerns – you *know*. So it is not without trepidation that I ask: Are your motives more sinister than you’re letting on?

  3. arch1 says:

    I’m perfectly ok w/ you deleting the above failed humor attempt. Though it might serve me right if you just left it.

    • John Baez says:

      I don’t mind jokes! In fact there’s a theory due to Geschwind and Galaburda that excess testosterone in the mother’s womb can cause the following symptoms in the child: left-handedness, allergies, asthma, short-sightedness, and high mathematical ability. I’ve suffered from all of these except perhaps the last.

      This hypothesis is controversial, with some studies supporting it and others not. Another supposed symptom is lysdexia.

  4. ashwin1729 says:

    ” People who identify as ‘either-handed’ score slightly lower overall in general intelligence testing”.

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