Since 2010, I’ve been maintaining a list of “interesting esoterica” – papers, books, essays and poems that I find interesting entirely on their own merits. It’s mainly bits of esoteric maths – hence the name – but I’ve also included quite a few things just because they have amusing titles. The main idea is that when I’m talking to someone and want to show them a cool thing that I’ve half-remembered, I can look up the exact reference: I’ve shared the paper “Orange peels and Fresnel integrals” more times than I can count (probably the same as the number of times I’ve eaten an orange).

# You're reading: Posts By Christian Lawson-Perfect

### Not mentioned on The Aperiodical this month, May 2016

Here are a few of the stories that we didn’t get round to covering in depth this month.

## Turing’s Sunflowers Project – results

Manchester Science Festival’s mass-participation maths/gardening project, Turing’s Sunflowers, ran in 2012 and invited members of the public to grow their own sunflowers, and then photograph or bring in the seed heads so a group of mathematicians could study them. The aim was to determine whether Fibonacci numbers occur in the seed spirals – this has previously been observed, but no large-scale study like this has ever been undertaken. This carries on the work Alan Turing did before he died.

The results of the research are now published – a paper has been published in the Royal Society’s Open Science journal, and the findings indicate that while Fibonacci numbers do often occur, other types of numbers also crop up, including Lucas numbers and other similarly defined number sequences.

### Maths Object: Nobbly Wobbly

My maths object this time is one of my dog’s favourite toys: the Nobbly Wobbly.

In the video, I said it was invented by a mathematician, but Dick Esterle’s bio normally goes “artist, architect, inventor”. I’ll leave it up to you to decide if Everyone’s a Mathematician.

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.

I’ve also found this Celebration of Mind livestream starring Dick Esterle from 2013 talking about all sorts of mathematically-shaped toys, including the Nobbly Wobbly.

### 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 soon that I should put in some stats tracking, to see if there were any interesting patterns in the data (and also to inflate my ego as the “games played” counter went up). I missed the first big spike in traffic, but on the 9th of March I wrote a script which saved a record of each game to a database.

The mad rush settled down quite quickly but there were still occasional spikes as different sites or people with lots of twitter followers found the game. Now, after two months, I’ve got data for just under 350,000 games. That’s a decent amount of information!

### 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 fill in (I estimate 10-15

minutes, and it is completely anonymous). The results will be made publicly

available later this year. I hope that it will help to focus our efforts as

a community by allowing us to work toward broadly agreed goals. I want to

get as representative and as large a sample of the world mathematical

community as possible. Please forward to your local colleagues.Please answer this survey if and only if you have been involved with a

mathematical journal as editor, reviewer/referee, author or reader in the

last 3 years. By “mathematical” we also mean to include theoretical

computer science and mathematical statistics journals, and disciplinary

journals used by applied mathematicians. Essentially, any journal covered

by Mathematical Reviews qualifies.

### 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.

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 poster by Bill Tavis.

### Steinberg’s conjecture is false

ConjectureEvery 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 pair of adjacent vertices have the same colour, using only three different colours. This is a counterexample to a conjecture of Richard Steinberg from 1976.

The problem was listed in the Open Problem Garden as of “outstanding” importance.

**Read the paper:** Steinberg’s conjecture is false

*via Parcly Taxel on Twitter*