
Welcome to the 131st edition of the Carnival of Mathematics, a monthly blogging carnival which scoots its way round the internet, rounding up maths-related blog posts from the month of January.

Welcome to the 131st edition of the Carnival of Mathematics, a monthly blogging carnival which scoots its way round the internet, rounding up maths-related blog posts from the month of January.

The talk summaries and slides from last November’s MathsJam conference are now online!
MathsJam is a monthly maths night that takes place in over 30 pubs all over the world, and it’s also an annual weekend conference in November. The conference comprises 5-minute talks on all kinds of topics in and related to mathematics, particularly recreational maths, games and puzzles.
The talks archive has now been updated with the 2015 talks – there’s a short summary of what each talk was about, along with any slides, in PPT and PDF format, and relevant links.
I’ve been looking forward to this one: cities in the mathematical domain. This is the kind of applied maths I can really get behind.
Samuel starts with Mike Batty of University College, London’s Centre for Advanced Spatial Analysis discussing how cities grow and organise themselves. The structure is frequently fractal; how does one calculate the dimension of a city?
From a top-level view of cities, he moves on to a low-level description of one of the biggest problem in cities: traffic (another thing that fascinates me). We get a glimpse of traffic waves, and the unfairness that the person responsible for the average jam doesn’t suffer from the effects. And we learn that Gábor Orosz (University of Michigan) tests his hypotheses using robots as well as simulations.

新年好, everyone! It was Chinese New Year on Monday, starting the year of the monkey. I didn’t really pay attention last year, so I didn’t know that it had been the year of the goat. I also wasn’t aware until just now when I looked it up that next year will be the year of the rooster.
In this 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 edition is a topical one, for Pancake Day (Shrove Tuesday, celebrated in the UK this year on 9th February).
Some of the best mathematical teasers are those which originate in a real-world problem – although the problem for pure mathematicians is that that happens much less often than it does for applied mathematicians, who are presented with interesting real-world problems all the time. That’s why it’s especially nice when a more pure one pops up, and that’s exactly what happened to mathematician Jacob E Goodman, back in 1975.
Before Christmas, the benign megasurveillance bods at GCHQ released a set of festive puzzles, in the form of a Christmas card and associated website. An initial nonogram puzzle led to a sequence of increasingly fiendish teasers, and solvers of the final set of puzzles were invited to email in their answers, with the correctest winning a fancy paperweight, signed book and, GCHQ were at pains to stress, not an Imitation-Game-style secret job offer.
For about 40 minutes of this week’s episode of Relatively Prime (Number 5 of 8, already? Good heavens!), Samuel Hansen looks like he’s managed to escape from his shameful, borderline criminal, past in Las Vegas. But he’s pulled back in for one last job, which is a debacle, of course.