My former student lent me their printed and bound copy of ‘Nine Chapters on the Semigroup Art’, my lecture notes for a tour through semigroup theory, in which they had marked various typos and minor errors, and points where they thought more explanation was required, so that I could make some improvements.

This was actually the first time I had ever seen it printed in full (photos attached). I had only printed individual chapters while working on it.

I think it looks pretty good, although I have improved the typography in the years since this copy was printed. In particular, I tightened the letter spacing used for theorem headers.

I released the #LuaLaTeX style "minos" I first developed for these notes (much revised and extended since) a few weeks ago: https://codeberg.org/ajcain/minos (Git repository) https://codeberg.org/ajcain/minos/releases (Documentation and source .zip/.tar.gz)

‘Nine Chapters’ itself is (and has always been) #OpenAccess: https://archive.org/details/cain_semigroups_a4_screen

#mathematics #typography #TeXLaTeX #semigroups

Just want to share the youtube channel of Thomas Kern, who does automata stuff. Here is a great video of him going through the Krohn-Rhodes theorem https://www.youtube.com/watch?v=3b1YRqDQ25w

#automata #semigroups

Regular Languages and Model Theory 28: The Krohn-Rhodes Theorem

YouTube
Kicking us off on our first session of the morning was Matt Parker @standupmaths who shared how he's planning to break the world record for the most digits of π calculated by hand, for next π day (see his other attempts here: https://www.youtube.com/playlist?list=PLhtC92GarkjyYbxI3-4qzIWIRbZaw4wuP). We also heard from Bob Huxley, who has also been thinking about π day, but this time on Mars where it turns out it's actually tomorrow! Annette Margolis then talked about her class' favourite (and least favourite) way to solve quadratic equations. John Hoskinson discussed Diffy Squares (https://mathforlove.com/2020/03/diffy-squares/) and adapted them to generalised diffy N-gons - for odd N, you get repeating cycles! Nobody has ever said the word 'diffy' more times in the space of 5 minutes. Alistair Bird @outofthenorm shared about a mathematician who got inspired in the bath (but not that one), and what his discovery meant (turns out, not much, but it did inspire some nice results around Fermat's Last Theorem). Read more here: https://outofthenormmaths.wordpress.com/2011/11/09/blitz-krieger/ Adam Atkinson talked about Misère Games, leading to his discovery of just how many semigroups of order 8 there are, inducting us all into membership of DOCTIAL (the Department of 'Crikey! That Is A Lot!'); and finally Harlan Connor got LOUD about signal processing - it's possible to have peaks in audio volume that are higher than the maximum value the system can store! #mathsjam #maths #pi #worldrecords #mars #piday #quadraticequations #classwork #teaching #diffysquares #baths #inspiration #misèregames #doctial #loud #signalprocessing #groups #monoids #semigroups #combinatorialgametheory
Matt calculates π

YouTube