From Relatively Prime

Principia Metropolica


Principia Metropolica

Your host Samuel Hansen loves cities. Small Cities, Dense Cities, New Cities, Twin Cities, Reborn Cities, he doesn’t care what type of city cities. He loves them all. This of course made it inevitable Samuel would at some point become interested in the intersection of cities and mathematics, and once he became interested in that intersection it became inevitable he would have to make a podcast featuring stories about it. And now here we are. Cause and effect, it really is a marvelous thing.

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The Dimension of Cities

Michael Batty is the chair of CASA, the Centre for Advanced Spatial Analysis . He is also the author of the books The New Science of Cities and Cites and Complexity. Samuel spoke to him about how cities grow, the similarity of cities and trees, and the fractal dimension of cities.

Listen to Samuel’s full interview with Michael Batty:

A Bunch of Two Parameter Driving Models

One truth about living in most cities is traffic, and quite often that truth is slow and all clogged up. As bothersome as all the traffic is, where there is a problem there is often interesting mathematics to do and in this case the mathematics is being tackled by University of Michigan professor Gabor Orosz. Samuel spoke with Gabor about why jams form, if there is any hope in the future for less of them, and what role robots in the hallways of the university play in his studies.

See the Sights

Maths in the City is an outreach program conceived by Marcus du Sautoy which shows groups the mathematics of London and Oxford. Samuel spoke with one of the tour guides, Thomas Woolley about the program and some of the mathematical sights you could see on one of the tours.

If these mathematical city tours sounds interesting to you, but you are not anywhere near London and Oxford do not fret as the Maths in the City website has you covered. There is an entire section where people can post their own examples of mathematics in cities all around the world, and you can easily search to see if there is any notable city mathematics near you.

The Universe of Urban Planning

Lisa Schweitzer is an Associate Professor of Urban Planning at the Sol Price School of Public Policy at USC. Samuel spoke to Lisa about the intersection of urban planning and mathematics, where mathematical tools are the most useful, where they fall short, and what the role of mathematics and statistics will be in urban planning moving forward.

Kolmogorov’s City

Kolmogorov complexity can be thought of as the smallest amount of computational resources needed to designate some object. Sim City is a computer game where you build and manage cities. Samuel Arbesman is a senior adjunct fellow at the Flatiron Center for Law, Technology, and Entrepreneurship at the University of Colorado. Yes, they do all come together.

Click here if you like spoilers(aka the article Samuel interviewed Samuel about)


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Other Duties as Assigned


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Other Duties As Assigned

Mathematician is an insanely broad job title It can encompass everyone from professors to government employees to podcast hosts.

And all of these different types of mathematicians, They do very different work, In very different ways.

Except for that one constant, they all do mathematics.

What Do They Do?

My friends Jess Charlton, Gabriel Siqueiros, Jen Bokoff, and Mike Wolf called me up and let me know just what it is they think mathematicians do all day.

Anna Haensch: The Academic

Anna Haensch is a Professor of Mathematics at Duquesne University, a mathematics writer, and co-host of The Other Half a pocast about the half of mathematics which helps you makes sense of your own life. Oh, and she tweets too.

Kristin Lauter: The Professional

Kristin Lauter is Principal Researcher and Research Manager for the Cryptography group at Microsoft Research and the President of the Association of Women in Mathematics. She also tweets.

Combinations and Permuations: The Fools

Combinations and Permuations was the first podcast Samuel ever hosted. He in no way thinks you should go back and listen to the inane and vulgar jokes he and his fellow mathematics graduate students made during the shows run, but he know he can’t stop you. For Relatively Prime he got some of the old favorites, Nathan Rowe, Sean Breckling, and Brandon Metz, back together in the mail room of UNLV CDC Building 7 to record an episode all about what mathematicians do all day.

Here is a longer cut of the silliness:


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Diegetic Plots: Chapter One


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Diegetic Plots: Chapter One

This episode of Relatively Prime is going to be delving into the humanistic side of mathematics. It is the first chapter in a recurring series Samuel is calling Diegetic Plots. Yes that is a super nerdy joke, and yes Samuel is super proud of it.

The Colors of Math

Gizem Karaali is an Associate Professor of Mathematics at Pomona College and an editor of The Journal of Humanistic Mathematics, a journal which looks at mathematics as a human endeavor with am emphasis on the aesthetic, cultural, and sociological aspects of mathematics. She read her poem The Colors of Math.

Division By Zero

Ted Chiang is a multiple Hugo and Nebula award winning science fiction author. Among his work is an amazing bit of math-fiction titled, Division By Zero. Samuel talked to Ted about where the idea for the story came from and what it was like to write about such an abstract mathematical idea. You can find the story in Ted’s short story collection Stories of Your Life and Others where you will also find a lot of other wonderful stories to read.

The interview is followed by a reading of Division By Zero by Jess Charlton, Kitty Stoholski, and Samuel.

Patent World Order

A black hole appears over Samuel’s desk as he tries to introduce the next segment and what appears is frightening.

The Mathematician’s Shiva

Stuart Rojstaczer has been a dishwasher, a college professor, and a grade inflation czar. He is now an author who’s debut novel was published in September 2014. The novel, The Mathematician’s Shiva, is the story of Rachela, the greatest mathematician of her age. It tells the story both of her time in a Soviet Gulag as a child and of the aftermath of her death. Samuel talked to Stuart about how he prepared to write about mathematicians, the importance of balancing all of one’s identities, and a little bit about Navier-Stokes.

A Taste of Mathematics

JoAnne Growney is a poet and a mathematician. She read her poem A Taste of Mathematics which can be found in her poetry collection Red Has No Reason


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####While the interviews in this episode Relatively Prime are licensed with a Creative Commons Attribution Share-Alike license, the authors reserve all rights for the poems and stories which appeared on this episode and if you want to reproduce or otherwise use their work please contact the authors to ask for their permission.



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Mathematics may be the most pure, the most abstract, the most ivory tower of all academic disciplines, but nothing, nothing is beyond the reach of politics. This episode of Relatively Prime looks at how politics effects mathematics and how mathematics can effect politics.

Presidential Pre-Requisites

Mathematics does not tend to be the focus of people who are aiming to become president of the United States, which reallay is not surprising. There are a lot of lawyers among the previous presidents, along with a few economics and business students. All of which do sound like more expected stepping stones to political office than a degree in mathematics. This does not mean they skip mathematical education in its entirety of course. Samuel spoke with Ronald Merritt of Athens State University about his research into the mathematical educations of US presidents and about which president has a proof included in Elisha Loomis’s book of proofs of the Pythagorean Theorem.

Boxers and Fighting Irish

Della Dumbaugh of University of Richmond tells us two stories of how Nazi Germany and the Boxer Rebellion changed the lives of individual mathematicians and the effects these life changes had on mathematics more broadly.

Surveillance Both Ways

Keith Devlin may not have born in the United States, but he is a very proud US citizen. He had only recently received his citizenship when the tragic events of September 11, 2001 came to pass. After the attacks, like a lot of other really smart people, Keith was contacted by the government and asked to lend his expertise to try and stop another attack. Keith talked to Samuel about went into his decision, whether or not he would make the same decision today, and some stuff which went down in Germany in the 70s.

And All of Gerry’s Man(dering)

Gerrymandering – the dividing of a state, county, etc., into election districts so as to give one political party a majority in many districts while concentrating the voting strength of the other party into as few districts as possible.

Few aspects of politics are as clearly open to mathematical analysis as gerrymandering. Just looking at district maps seems to scream for geometric analysis, and there really are a lot of different tests out there. Samuel spoke to David Austin about some potential gerrymandered districts and ways to test for them, then things got a bit bizarre. Samuel also sat down with Jonathan Hodge to talk about a technique Hodge helped develop to test for gerrymandering called the Convexity Coefficient.

Not all of the ways to test for possible gerrymandering rely on geometry. Duke University Professor Jonathan Mattingly and his former student Christy Vaughn, she is currently a graduate student at Princeton, decided to use probability theory to check to see if the districts used in North Carolina’s 2012 elections had been drawn fairly. The results were eye opening.


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Your Daily Recommended Math


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Your Daily Recommended Math

We all use mathematics everyday. At least that is what we all like to tell our friends who ask us, “What good is math anyway?” The problem is so much of this everyday mathematics is, how should I say this, non-obvious. No one thinks they are doing mathematics when they figure out the larger peanut butter is not actually a better deal than the smaller size or when they cut across the intersection diagonally to save time or when they decide to ask that friend they don’t really talk to much to spread the word about their new project because that friend has more friends than they do(not that I have any history doing this last one, no history in doing it at all). Sure those are just algebra, geometry, and network analysis problems deep down, but they are also just normal every issues. In this episode of Relatively Prime we look at three regular, everyday problems and use mathematics to make them a bit more comfortable, a bit more pleasant, and, in the case of the first story, a bit more delicious. Oh, and we have a couple quick pieces of advice about how to make pumping gas fun and tipping more secure.

Parker’s Palindromic Pumping

Samuel was talking to Matt Parker, on of the nerds in The Festival of the Spoken Nerd and author of Things to Make or Do in the Fourth Dimension which sadly is only a three dimensional book, and asked him if he had any everyday tasks which mathematics could make better. His answer will change how you pump gas forever.

But I Want That Piece

Say you are living in a new city and you haven’t made any new friends yet and your birthday is coming up. This was the exact situation Samuel was in last year. He still wanted to have a cake though, but as he was by himself Samuel was worried if he cut his cake in the traditional way it would go stale. Enter Alex Bellos, Guardian Columnist, author of Here’s Looking at Euclid, The Grapes of Math, and, with Edmund Harriss, the math coloring book Snowflake Seashell Star, to tell Samuel about Sir Francis Galton’s perfect cake cutting technique.

Of course since Samuel recorded the interview with Alex before his birthday something was going to have to happen to make it not relevant. In this case it was a happy occurrence, Samuel actually made a friend with whom he could celebrate his birthday. Which was awesome, except it meant Alex’s cake cutting method wasn’t going to be too useful. Samuel wasn’t going to have a birthday without a mathematically appropriate cake cut though so he called up Steven Brams to determine how to fairly divide his cake between him and his new friend.

Just Choose a Spot Bob

Of course this meant Samuel needed to go get his birthday cake, and in order to do that he was going to need to find himself a parking spot. For most people this is an everyday problem, but since Samuel usually rolls out of bed and lands in front of his microphone he needed some help to choose the best spot to choose when buying his cake. Thankfully Laura Mclay, who writes the blog Punk Rock Operations Research, had his back or he would probably still be driving around the bakery’s parking lot.

Should We Stay or Should We Go

Imagine this: It is a Thursday night and the pub a few blocks away has an Irish music night you really like, but it is a small pub and when there are a lot of people there you don’t enjoy yourself. Should you go to the pub or should you stay home? This is the exact problem W. Brian Arthur found himself having in Santa Fe with the El Farol Bar in the early 90s and being trained in economics and mathematics Brian did the logical thing, he wrote a paper on it.

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