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Graphical linear algebra: from matrices to monoids (graphicallinearalgebra.net)
317 points by jxub on Feb 16, 2018 | hide | past | favorite | 15 comments



I'll always recommend 3blue1brown's incomparable videos on linear algebra: https://www.youtube.com/watch?v=kjBOesZCoqc&list=PLZHQObOWTQ...


The best, hands down on YouTube.


Really interesting. As well he seems to re-derive and implementation of Forth.

In episode 6, Right under the diagran for Crema di Marscapone he has a formula.

Does anyone that uses Forth know if it has that circle-plus operator? It seems to really lend to conciseness - and I hadn't remembered anything like it last time I looked at Forth.

https://graphicallinearalgebra.net/2015/05/06/crema-di-masca...


It’s not surprising—there’s a deep relationship among concatenative languages, Hughes’ arrows, combinator calculus, category theory, linear algebra, logic, even topology. I haven’t read through this but I guess the ⊕ operator would be “* * *” (parallel composition) in arrow notation; in Haskell it has the type “Arrow a ⇒ a b c → a b′ c′ → a (b, b′) (c, c′)”, or “(b → c) → (b′ → c′) → (b, b′) → (c, c′)” specialised to the function arrow.


There's no operator because composition and direct sum are implicit in the order of your program words.


I've been looking for a categorical take on neural networks and have found nothing, and this might get me started into translating some existing NN papers to CT.



Amazing! Thank you. And I'll say, CT is so much better on the eyes than matrix/linear calculus.


How closely is this related to Penrose's graphical tensor notation?

https://en.wikipedia.org/wiki/Penrose_graphical_notation


I think the major difference is this notation has the count of loose wires corresponding to dimension, and Penrose notation has the count of loose wires corresponding to tensor valence.

Here, a diagram with 1L and 2R wires corresponds to a 2d-vector, in Penrose's notation it would correspond to a (1,2) tensor that takes kd-vectors to kXk matrices.

But... they certainly have a similar feel. I wonder if you could build up the Penrose notation out of this.


This was absolutely amazing! Reminds me of lambda maths a lot.


What problem does graph-representation solve?


The structure is more obviously modular and the algebraic laws become topological phenomena, which makes it easier to consider more complicated structures than vector spaces.


You might be interested in Leavitt path algebras!


From what I can tell, this series is a kind of intro to category theory by way of linear algebra




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