# You're reading: Blackboard Bold

### Open Season – The Perfect Cuboid

In this short series of articles, I’m writing about mathematical questions we don’t know the answer to – which haven’t yet been proven or disproven. This is the second article in the series, and considers a less well-known variant on an extremely well-known problem.

Ask anyone to name a theorem, and they’ll probably come up with one of the really famous ones, like Pythagoras’ theorem. This super-handy hypotenuse fact states that for a triangle with sides A, B and C, where the angle between A and B is a right angle, we have $C^2 = A^2 + B^2$. This leads us on to a nice bit of stamp-collecting – there are infinitely many triples of integers, A, B and C, which fit this equation, called Pythagorean Triples.

One well-known generalisation of this is to change the value $2$ to larger values, and go looking for triples satisfying $C^n = A^n + B^n$. But don’t – Andrew Wiles spent a good chunk of his life on proving that you can’t, for any value of $n>2$, find any such triples. The statement was originally made by Pierre De Fermat, and while Fermat famously didn’t write down a proof, it was the last of his mathematical statements to be gifted one – hence the name ‘Fermat’s Last Theorem’ – and proving it took over 350 years.

### Foldable Dodecahedron Calendar made in LaTeX

If anyone still hasn’t sorted themselves out with a calendar for 2013 – come on people, it’s February! – there’s a nice example of one here. It’s a dodecahedron which, once assembled, you can presumably orient to display the correct month (or the incorrect month, if you’re an impish sort).

The best thing about it for fans of LaTeX (the majestic mathematical markup language of kings) is that this thing is written entirely in LaTeX, using the TikZ package to create the graphics.

Download: PDF and TeX files, as well as all necessary packages, are available from TeXample.net.

(If you can’t compile the calendar yourself and want an up-to-date version, click on the Open in writeLaTeX link).

### ‘Of little practical value’?

Some mathematics, pictured here being hard to illustrate in news coverage

As the heady excitement of the dawn of a forty-eight-Mersenne-prime world dims to a subdued, albeit slightly less factorable, normality, I have taken the opportunity to see what we can learn about the British press’s attitude and ability when it comes to the reporting of big numbers ending in a 1.

Overseas readers may not be aware that the UK’s public service broadcaster, the BBC, is funded by a mandatory annual £145.50 tax on all television-owning households. Therefore, it would be disappointing if some of these funds were not channeled into reporting the discovery in at least five or six separately-produced broadcasts across the organisation’s various radio and television outlets.

### Open Season – Singmaster’s Conjecture

Science and maths are all about finding things out. Mathematics in particular is about making statements, and then determining their truth (or falsity). Finding a proof, or disproof, of a mathematical theory can be as simple as finding a counterexample, or it can take hundreds of authors tens of thousands of pages.

In this short series of articles, I’m going to write about some mathematical questions we don’t know the answer to – which haven’t yet been proven or disproven. Hopefully you will find it interesting, and maybe someone will even be inspired to delve deeper and find the answers themselves.

### Carnival of Mathematics 94

Welcome to the 94th Carnival of Mathematics! This month the carnival has once again trundled in to Blackboard Bold at the Aperiodical, though this time with myself rather than Katie at the helm (carnivals have helms).

### Mathematical Christmas Cracker Jokes

At this time of year, lame and/or groan-worthy jokes come to the fore, and are completely acceptable, and in some cases encouraged, provided they’re preceded by a bang noise and read out from a tiny piece of paper.

Rummaging around on my computer today, I found a set of mathematical Christmas cracker jokes I wrote for a party thrown for a group of mathematicians a couple of years ago, where I hacked apart a set of crackers and replaced the toys with tiny slide rules, the paper hats with ones cut into fractal curves along the top, and the existing terrible jokes with terrible mathematical ones. I thought I’d share them with you all, since they’re more likely to be appreciated by maths fans.

### Follow Friday, 16/11/12

Who’s really good at the internet? I mean, really? Do any of us have a handle on that crazy pile of ones and zeroes that sucks away so much of our leisure time while simultaneously providing us with access to all of human knowledge at the click of a button? In another misguided attempt to help us all clamber on top of the ever-increasing pile of data and facts (and opinions), here’s some more recommendations of who to follow on Twitter, and some links and funny things they have recently Twittered.