# MathsJam Gathering 2018

This is a list of talks given at the 2018 MathsJam Weekend, along with a brief description, and links to slides or other relevant content where we have them. If you spot any mistakes on this page, or would like to update the description of your talk, use the 'Edit this page' link at the bottom with a GitHub account to propose changes and make a pull request.

There is also a Cake page here with the photos of cakes entered in the cake competition, and a PDF of the MathsJamJam Songbook from 2018.

The gathering took place on 17th-18th November 2018.

## SATURDAY

### SESSION 1a : 14:00

#### Phil Harvey : Initialistic Determinism

Phil has noticed a correlation between your surname initial being in the first part of the alphabet, and your chances of success in life, and shows some graphs indicating there might be something to the theory.

#### Alison Kiddle : Pastamathics

Spaghetti on toast is everybody's favourite quick and easy tea, but have you ever stopped to analyse the maths on your plate? Alison has analysed the distribution of digits in the average tin of spaghetti numbers, and created a Geogebra implementation of the process of making fusilli pasta.

#### Mick de Pomerai : Mass Of A Black Hole

Mick presents a short history of ideas on orbits & gravity, to introduce the maths needed to calculate the mass of Sagittarius A* from Keck telescope data (which is given out as a handout).

#### Hugh Hunt : Chain On A Cone

A thin light chain with a heavy pendant is displayed in a jeweller's shop hanging on a smooth conical stand. What is the cone angle above which the chain will slip off the stand under the weight of the pendant down the slope? Hugh demonstrates some nice physical models, and shows that the line the chain makes on the surface is actually a straight line if you cut and open the cone.

#### Claire Cohen : How Lucky Is The Bonus Ball

Claire has been running a workplace Bonus Ball raffle at work, and has studied the data - what kind of numbers are commonly picked, what are people's reasons for choosing them, and how do they compare to the actual results of the bonus ball draw.

#### Laurence O'Toole : Guessing With Lies - A Magic Trick

You may be familiar with the classic Christmas cracker trick where your volunteer picks a number, and tells you which of the cards you show contains their number. Laurence presents a twist on this, in which one of your answers has to be a lie. How does it work?

#### Adam Townsend : The Coin Distribution Problem Revisited

Why do self-checkout machines give the worst change? Are they better in other countries? Using real price data from the ONS, Adam asks: would getting rid of the penny fix this problem, or is there a better, more ridiculous solution? (Of course there is, and Adam's worked out which coin we'd need to add).

#### Martin Harris : Pleasing Pictorial Proofs And Ptolemy's Ptheorem

Martin shares some examples of pictorial proofs, and has come up with a new one for Ptolemy's Theorem of Cyclic Quadrilaterals.

### SESSION 1b : 15:10

#### Samuel Hansen : The Long Tail Of Mathematical Citations

Samuel explores how age and citation counts are related in highly cited mathematical papers, with a specific focus on the way mathematical research ages - some famous maths papers were hardly cited at all until years after they were published.

#### Gavan Fantom : Doing Trigonometry In Your Head While Trying To Land A Plane

There's a lot of maths involved in flying a plane. Fortunately most of it can be done on the ground, but there are some calculations that pilots do while in the air. Imagine you're on final approach, less than a minute from the runway. Can you use trigonometry to decide if it's safe to land?

#### Rob Low : A Minus Times A Minus Is A Pain

We all learn quite young that a minus times a minus is a plus, and the reason given by the teacher is all too often some variation on "Because I say so". Why should we believe it? Rob explains why.

#### Eleanor Doman : A Needling Problem From Embroidery

Blackwork is a type of embroidery that traditionally is supposed to look the same on the front and back of the material and is usually based off geometric patterns. But what kind of patterns can we use, and can we prove mathematically that they will look the same on both sides.

#### Kevin Houston : Where Was That taken?

Can we use mathematics to determine where the photographer stood to take a photograph? Kevin shows some examples.

#### Mike Frost : Piet Hein - Pirate

Mike discovered a hotel in the Netherlands had a conference suite named for Piet Hein. Why did a Dutch hotel have a room named for a Danish mathematician much revered by recreational mathematicians? It turns out, Piet Hein the mathematician and Piet Hein the pirate were two different people.

#### Peter Rowlett : Counting Caterpillars

A robot caterpillar Peter bought for his three-year-old purports to have "endless combinations". Peter shows that it has 5023 combinations (not a completely straightforward combinatorics problem), and observes that 5023 is finite.

#### Tung Ken Lam : Action Modular Origami

This talk explains what action modular origami is and how it intrigues and delights. What are its origins and current developments? Briefly, action modular origami involves folding and joining paper together (without cutting or gluing) into sculptures that move or change shape. They can be put in six categories (ignoring things that you throw): sliders; flexagons; rotating rings; magic wallet models; spinners/wheels, and 3D shapeshifters.

### SESSION 1c 16:20

#### Ben Sparks : Sparks Does Maths, And Possibly Geogebra...

Ben shares a puzzle in which a mouse swimming in a pond tries to escape from a cat on shore. Can it get away?

#### Rachel Wright : An Unexpected Parallel

Pierre de Fermat was not the only person to make an off-hand comment that gave subsequent generations a thundering headache... a passing remark in an old book on embroidery describes something that no-one has yet been able to work out how to do.

#### Derek Couzens : Using Maths To Solve A Socially Embarrassing Situation

Derek demonstrates how to turn your trousers inside-out without taking your feet off the floor. (Needs special trousers.)

#### Alex Burlton : 180 Ways Not To Model A Darts Player

What happens when you are mediocre at darts and have too much time on your hands? Alex discusses an attempt to generate an equally crummy opponent - with some surprising results.

#### Christian Lawson-Perfect : Zeckendorf Cup Arithmetic

Having a baby isn't a complete distraction from maths - Christian shares his adventures with a set of nested stacking cups, and works out how many ways you can stack them subject to various constraints.

#### Steve Plummer : 42

Not quite life, the universe and everything - Steve shares some surprise appearances by a particular integer, including in Alice in Wonderland and in Philip Astley's trick riding.

#### Barney Maunder-Taylor : Collapsible Polyhedra

A demonstration of various homemade polyhedra - all the Platonic ('Flat-onic') solids and some of the Archimedeans - that fold flat.

### SESSION 1d : 17:30

#### Louise Mabbs : Jacob's Ladders - Fabric And Paper Experiments

Louise demonstrates a fabric version of the traditional Jacob's Ladder 2-strip fold she developed in 2006 for a fabric origami book. She's developed it since, and the resulting techniques cover origami, braiding, weaving and several other skills and some fascinating structures.

#### Tom Reddington : Banach-Tarski: Just Make Peace With It

The Banach-Tarski Paradox has caused many arguments and probably several pub fights, due to people's reluctance to accept it. Tom convinces us all it really is true.

#### Alison Eves : Magic Magic Squares

A quick introduction to magic squares, some interesting facts, and some links to magic squares in art and history.

#### Sydney Weaver : The Sound Of Silence

An exercise in the 4 memory types demonstrated by the Rubik's Cube, and a parody of a well known song.

#### Alaric Stephen : Generating Hard Puzzles Using Graph Theory

Alaric highlights a method for making word based puzzles to an arbitrary level of difficulty, using a quirk of Hamiltonian graphs.

#### Colin Wright : e's In A Twist

Colin demonstrates several ways to derive Euler's identity (e^{iπ}=-1) - including square roots, simple algebra, and a step in an odd direction.

## SUNDAY

### SESSION 2a : 09:00

#### Katie Steckles : The Unwanted Solid

You may have heard of Archimedean solids - a category of thirteen 3D shapes with particular properties. But did you know that there's actually a fourteenth Archimedean solid? Katie argues the case for allowing the Pseudorhombicuboctahedron to join the club.

#### Martin Chlond : The Travelling Salesman Problem: A Couple Of Whimsical Applications

A couple of quirky uses of TSP algorithms - including ways to make art!

#### Jonathan Welton : Platonic Moboids

Using paper, scissors and glue, platonic moboids knot together two familiar mathematical concepts, and produce a third.

#### Callum Mulligan : Ray Casting And Rabbits

Ray Casting is used in a multitude of ways to solve intersection tests. One of Callum's students did something brilliant and used it in an alternative way. Callum shares some fun uses for Ray Casting (including how it can be used to spawn Rabbits in videogames!) and the mathematics behind it.

#### Tim Chadwick : Numberblocks

Tim shares his enthusiasm for CBBC maths staple Numberblocks. We're all hooked now.

#### Tarim : Snake Bridges

There are special bridges called snake bridges which help avoid tow-ropes getting tangled when your horse changes bank - it turns out, canal engineers used topology before the term was even coined!

### SESSION 2b : 09:55

#### Adam Atkinson : Conspiracy Of Silence

Lots of people know about discrete and continuous probability distributions. THEY don't want you to know about the third kind: singular distributions.

- Adam's slides (PDF)
- Adam's video 1 (MP4)
- Adam's video 2 (MP4) (The videos need to be downloaded to be played.)

#### Will Kirkby : Digital Art And Distance Functions

A brief exploration of signed distance functions and their use in real-time computer graphics.

#### Jo Morgan : Changing Contexts

A quick look at how the contexts used in school mathematics questions have changed over the years.

#### Pedro Freitas : Ubiquitous Permutations

Composer Olivier Messaien's "Interversions" has the same structure as the "Milk Shuffle With Drop" used for card tricks... and the same permutation can also be used to generate the Matthieu groups!

#### Alistair Bird : The Four-And-A-Half Colour Theorem

The truth of the famous 4-colour theorem immediately implies that the 4½-colour theorem is also true. But how can you have half a colour? And why bother investigating a theorem when we already know the answer? Alistair shares the problem: If each country has a flag with two colours on, can you arrange the colours so that adjacent countries' flags don't share any colours?

#### Michael Gibson : A New Trick For Old Dogs

The "well known" Five-Card-Trick involves a volunteer choosing 5 cards and giving them to Magician A who looks at them and arranges them with 4 cards showing and 1 hidden. Based on this Magician B can then say what the hidden card is. Michael describes and performs a new version of this trick in which only 1 card is showing and Magician B has to say what all 4 of the hidden cards are.

### SESSION 2c : 10:50

#### Matthew Scroggs : Mathsteroids

Matthew presents several different ways to represent a sphere as a flat surface using Mathsteroids, an asteroids-style game in which you can play on a sphere with different representations.

#### Stefania Delprete : MathsJam In Python

Stefania relates how the Berlin and Turin MathsJams solved some puzzles using Python.

#### Stuart Eves : Do The Planets Fit Between The Earth And The Moon?

Is there room between the Earth and the Moon to fit all the planets in the solar system? Possible answers are "yes", "no", or "sometimes". Stuart reveals the answer.

#### Francisco Albuquerque Picado : A Comic, A Painting, Triangles, And Squares

A comic leads to a painting, which allows us to discover a connection between triangular numbers and sums of squares.

#### Pat Ashforth : Extending Tables

Pat shows off a piece of mathematical furniture from her collection - an extendable table with an aperiodic tiling, which works whether the table is extended or not!

#### Tiago Hirth : From Pebbles To Nimbers and Stars

A quick run through 500 years of history related to the game of Nim, and an invitation to participate in Recreational Mathematics projects.

### SESSION 2d : 11:45

#### Colin Beveridge : A Proof Without Words

Colin proves 1^{2} + 2^{2} + 3^{2} + ... + n^{2} = n(n+1)(2n+1)/6 through the medium of mime.

#### Robie Basak : Measuring Sticks

Robie demonstrates how to make a slide rule.

#### Andrew Macdonald : So, About Ghandi

Addition, subtraction and negative numbers in binary computing can be difficult. Andrew relates the tale of why the programmers of the game Civilisation made Gandhi such a fan of nuclear weapons...

#### Sam Hartburn : Battle Of The Slinkies: Paper Vs Plastic

Can an origami slinky outperform a cheap plastic one? Sam experiments.