# Newcastle MathsJam February 2012 Recap

February’s MathsJam was loads of fun! We had a record attendance of 14 cheery people who just about managed to fit around the biggest table in the Charles Grey.

After last month’s puzzlocalypse, which left me for over a week unable to count the toes on my feet, I wanted to have a nice relaxed evening.

# Interesting Esoterica Summation

I feel like it’s time to do another summary of my recent additions to the Interesting Esoterica collection.

A reminder of what it’s all about: every now and then I encounter a paper or a book or an article that grabs my interest but isn’t directly useful for anything. It might be about some niche sub-sub-subtopic I’ve never heard of, or it might talk about something old from a new angle, or it might just have a funny title. I put these things in my Interesting Esoterica collection on Mendeley.

In this post the titles are links to the original sources, and I try to add some interpretation or explanation of why I think each thing is interesting below the abstract.

Some things might not be freely available, or even available for a reasonable price. Sorry.

# MATH PROBLEMS?

Maths in the City posted this on twitter:

In order to make a number we can call, we need both of $n=(10x)(13i^2)$ and $m=\frac{\sin(xy)}{2.362x}$ to be integers.

# Putting all the world’s water in buckets

Following this pair of tweets about water:

The obvious question is, at what point are the two numbers the same? Or,

If you put all the Earth’s water into containers of the same size so that each container carries as many atoms of water as there are containers, how big is each container?

# Newcastle MathsJam January 2012 Recap

January’s MathsJam was a bit massive. It’s now a week later and I’ve only just gathered enough thoughts together to do this writeup.

There were nine of us this month, all but one of whom either maths students or lecturers. A major theme of the night was of professional mathematicians or nearly-professional mathematicians forgetting basic high-school methods. This led to quite an intense session of puzzling and proving.

Things didn’t start out that way, though. A few weeks ago I found the website of a mathematician in Illinois called Alan Schoen, and his page about Lominoes. They’re a pretty interesting set of shapes! I ordered a couple of sets and they arrived just in time for the MathsJam.

# How to get beautifully typeset maths on your blog

Lots of people have blogs where they talk about maths. Lots of these people just use plain text for mathematical notation which, while it gets the point across, isn’t as easy to read or as visually appealing as it could be. MathJax lets you write LaTeX and get beautifully typeset mathematical notation. And it’s really really easy to set up: you just need to paste some code into the header of your blog’s theme. To make it really really really easy, I’ve written some very detailed instructions of what to do for each big blogging service. (If you’re reading this after I wrote it, which you definitely are, beware that the interfaces I describe may have changed, so the advice below might be inaccurate. If it is, or if you’re just having trouble following along, please leave a comment below.)

# Testing MathJax

Maths between dollars is inline: $$\sum_{k=1}^n k = \frac{n(n+1)}{2}$$.

Maths between slash-square-brackets is display: $\sum_{k=1}^n k = \frac{n(n+1)}{2}$

# Interesting Esoterica Summation

I’m going to try collecting additions to my Interesting Esoterica collection in let’s-say-weekly posts. I’ll link to each item, maybe paste its abstract, and write a sentence or two about it. Let’s see if it catches on. I’m not sure if I’ll have the will to do this regularly. I’m in a bit of a getting-things-done mood today.

As this is the first one, and I’ve added loads of stuff in January, for this first post I’m using everything I’ve added since the New Year. Future posts shouldn’t be anywhere near as long.

I should explain what the Interesting Esoterica collection is about. Basically, it’s where I put interesting stuff that I find. Most of the entries are proper research papers, though quite often a funny title is enough to merit inclusion. I certainly don’t read or even understand everything that goes in. I reckon it’s a fairly even split between stuff that’s really fascinating maths and stuff that’s just… esoteric. It’s a bit like a research-level maths version of QI.

The titles are links to the original sources, and I’m trying to sprinkle explanatory links throughout the rest of the text.

# The sign on my office door

Recently, someone left my office at Newcastle University and a new person took their place, so we needed a new sign on our front door. I wanted to do something clever with it, but it needed to be instantly legible to lost supervisors trying to find their students.

My first thought was that since there are seven of us, something to do with the Fano plane would look good. Our names didn’t have enough of the right letters in the right places for it to work, though.

That got me thinking about the Levenshtein distance. The Levenshtein distance between two strings is a measure of how many changes you need to make to one to end up with the other. I wrote a Python script which calculated the distance between each pair of names: