My maths object this time is one of my dog’s favourite toys: the Nobbly Wobbly. It’s a particularly pleasing rubbery ball thing made of six interwoven loops in different colours, invented by Dick Esterle. On Google+, various people told me the unexpected fact that the outer automorphism group of $S_6$ is hiding inside this dog toy.…
Katie’s Binary Nails Tutorial – and a puzzle
I’ve just posted my latest YouTube video, in which I explain how to use binary numbers to jazz up your nail varnish: Alongside this video, I also have an associated puzzle for you to think about.
Are you sure 51 isn’t prime? – Analysing the results of the “Is this prime?” game
Two months ago, I bought isthisprime.com and not only set up the internet’s fanciest primality-checking service, but also invented a rather addictive game. It quite quickly went viral, or as relatively viral as a maths game can get, with people tweeting their high scores and posting the link to reddit and Hacker News. I realised fairly…
Puzzlebomb – May 2016
Puzzlebomb is a monthly puzzle compendium. Issue 53 of Puzzlebomb, for May 2016, can be found here: Puzzlebomb – Issue 53 – May 2016 The solutions to Issue 53 can be found here: Puzzlebomb – Issue 53 – Solutions – May 2016 Previous issues of Puzzlebomb, and their solutions, can be found at Puzzlebomb.co.uk.
Ever been involved in publishing research? Answer this survey of mathematical publishing priorities
From Mark C. Wilson of the University of Auckland, a little public service announcement for anyone who’s ever been involved with a mathematical journal. Dear colleagues, There is much dissatisfaction with the current state of research publication, but little information on community attitudes and priorities. I have started a survey which I hope you will…
Kickstart the Mandelmap poster: a vintage style map of the Mandelbrot set
Here’s something fun you might want to spend some money on: a poster of the Mandelbrot set, in the style of an old-fashioned navigation chart. https://www.kickstarter.com/projects/billtavis/mandelmap-poster-a-vintage-style-map-of-the-mandel The Kickstarter has already racked up many multiples of the original funding goal with three weeks still to go, so it’s at the “effectively a pre-order” stage. The posters start at \$26. Kickstarter: Mandelmap…
Steinberg’s conjecture is false
Conjecture Every planar graph without 4-cycles and 5-cycles is 3-colourable. Nope! In a paper just uploaded to the arXiv, Vincent Cohen-Addad, Michael Hebdige, Daniel Kral, Zhentao Li and Esteban Salgado show the construction of a graph with no cycles of length 4 or 5 which isn’t 3-colourable: it isn’t possible to assign colours to its vertices so that no…