Applications are open for the ACT Applied Category Theory Research School 2018! And because arithmetic science and geometric science are connected, and support one another, the full knowledge of numbers cannot be presented without encountering some geometry, or without seeing that operating in this way on numbers is close to geometry; the method is full of many proofs and demonstrations that are made with geometric figures. Fibonacci, preface to Liber Abaci (first published 1202, 1228 manuscript translated by Lawrence E. Sigler) If you like this blog, please subscribe to get email updates when new articles are published. You will find a subscription link at the bottom of this page. Graphical linear algebra is a work in progress, and there are many open research threads. We are looking for PhD students, so please consider applying! This blog is written in English. To read and contribute to translations (Dutch, French, German,…) see this page by Vincent Verheyen. Introduction Episode 1 – Makélélé and Linear Algebra Episode 2 – Methodology, Handwaving and Diagrams Adding and Copying Episode 3 – Adding (Part 1) and Mr Fibonacci Episode 4 – Dumbing Down and Magic Lego Episode 5 – Spoilers, Adding (Part 2) and Zero Episode 6 – Crema di Mascarpone and Diagrammatic Reasoning Episode 7 – Copying, Discarding and The Slogan Episode 8 – When Adding met Copying… Episode 9 – Natural numbers, diagrammatically Matrices and PROPs Episode 10 – Paths and Matrices Episode 11 – From Diagrams to Matrices Episode 12 – Monoidal Categories and PROPs (Part 1) Episode 13 – PROPs (Part 2) and Permutations Episode 14 – Homomorphisms of PROPs Episode 15 – Matrices, diagrammatically Episode 16 – Trust the Homomorphism, for it is Fully Faithful Integers and Relations Episode 17 – Maths with Diagrams Episode 18 – Introducing the Antipode Episode 19 – Integer matrices Episode 20 – Causality, Feedback and Relations Episode 21 – Functions and Relations, diagrammatically Episode 22 – The Frobenius Equation Episode 23 – Frobenius Snakes and Spiders Fractions and Spaces Episode 24 – Bringing it all together Episode 25 – Fractions, diagrammatically Episode 26 – Keep Calm and Divide by Zero Episode 27 – Linear Relations Episode 28 – Subspaces, diagrammatically Episode 29 – Dividing by zero to invert matrices Episode 30 – The essence of graphical linear algebra Redundancy – A trilogy by Jason Erbele Episode R1 – Redundancy and Zebra Snakes Interlude – string diagrams and resource-sensitive syntax Why string diagrams? Sequences and Signal Flow Graphs Episode 31 – Fibonacci and sustainable rabbit farming Out of order (for now) Orthogonality and projections Eigenstuff, diagrammatically Contributions Determinants and the Lindström-Gessel-Vienot Lemma – by Solomon Maina Offtopic Sometimes this blog actually looks like a blog. 16 September 2016 – Leicester and the battle for universities 16 April 2017 – …, a monoid is a category, a category is a monad, a monad is a monoid, … 10 May 2017 – 1st Workshop on String Diagrams in Computation, Logic, and Physics 3 October 2018 – ACT 2018 – Applied Category Theory Research School