# Pixel Art, Gothic Circle Patterns, and First Past the Post

For this week’s Math Munch, we have a re-run from four years ago– which just happened to be our first anniversary on Math Munch and the end of the previous presidential election. What were we thinking about then, and what are we thinking about now?

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Welcome to this week’s Math Munch!

Guess what? Today is Math Munch’s one-year anniversary!

We’re so grateful to everyone who has made this year so much fun: our students and readers; everyone who has spread the word about Math Munch; and especially all the people who do and make the cool mathy things that we so love to find and share.

Speaking of which…

Mathematicians have studied the popular puzzle called Sudoku in numerous ways. They’ve counted the number of solutions. They’ve investigated how few given numbers are required to force a unique solution. But Tiffany C. Inglis came at this puzzle craze from another angle—as a way to encode pixel art!

Tiffany studies computer graphics at the University of Waterloo in Ontario, Canada. She’s a PhD candidate at the Computer Graphics Lab (which seems like an amazing place to work and study—would you check out these mazes!?)

Tiffany C. Inglis, hoisting a buckyball

Tiffany tried to find shading schemes for Sudoku puzzles so that pictures would emerge—like the classic mushroom pictured above. Sudoku puzzles are a pretty restrictive structure, but Tiffany and her collaborators had some success—and even more when they loosened the rules a bit. You can read about (and see!) some of their results on this rad poster and in their paper.

Thinking about making pictures with Sudoku puzzles got Tiffany interested in pixel art more generally. “I did some research on how to create pixel art from generic images such as photographs and realized that it’s an unexplored area of research, which was very exciting!” Soon she started building computer programs—algorithms—to automatically convert smooth line art into blockier pixel art without losing the flavor of the original. You can read more about Tiffany’s pixelization research on this page of her website. You should definitely check out another incredible poster Tiffany made about this research!

To read more of my interview with Tiffany, you can click here.

Cartoon Tiffany explains what makes a good pixelization. Check out the full comic!

I met Tiffany this past summer at Bridges, where she both exhibited her artwork and gave an awesome talk about circle patterns in Gothic architecture. You may be familiar with Apollonian gaskets; Gothic circle patterns have a similar circle-packing feel to them, but they have some different restrictions. Circles don’t just squeeze in one at a time, but come in rings. It’s especially nice when all of the tangencies—the places where the circles touch—coincide throughout the different layers of the pattern. Tiffany worked on the problem of when this happens and discovered that only a small family has this property. Even so, the less regular circle patterns can still produce pleasing effects. She wrote about this and more in her paper on Gothic circle patterns.

I’m really inspired by how Tiffany finds new ideas in so many place, and how she pursues them and then shares them in amazing ways. I hope you’re inspired, too!

 A rose window at the Milan Cathedral, with circle designs highlighted. A mathematical model similar to the window, which Tiffany created. An original design by Tiffany. All of these images are from her paper. Here’s another of Tiffany’s designs. Now try making one of your own!

Using the Mathematica code that Tiffany wrote to build her diagrams, I made an applet where you can try making some circle designs of your own. Check it out! If you make one you really like—and maybe color it in—we’d love to see it! You can send it to us at MathMunchTeam@gmail.com.

(You’ll may have to download a plug-in to view the applet; it’s the same plug-in required to use the Wolfram Demonstrations Project.)

Finally, with Election Day right around the corner, how about a dose of the mathematics of voting?

I’m a fan of this series of videos about voting theory by C.G.P. Grey. Who could resist the charm of learning about the alternative vote from a wallaby, or about gerrymandering from a weasel? Below you’ll find the first video in his series, entitled “The Problems with First Past the Post Voting Explained.” Majority rule isn’t as simple of a concept as you might think, and math can help to explain why. As can jungle animals, of course.

Thanks again for being a part of our Math Munch fun this past year. Here’s to a great second course! Bon appetit!

PS I linked to a bunch of papers in this post. After all, that’s the traditional first anniversary gift!

# Gödel, Other Crazy Paradoxes, and Math Factor

Welcome to this week’s Math Munch!

Math can be confusing. Everyone knows that. And, actually, that’s what lots of people love about it. Some things in math are more confusing than others. One such thing, in my opinion, is a theorem developed by this kinda creepy-looking guy:

His name is Kurt Gödel, and he’s responsible for a theorem that basically says: You know how you thought we had rules for arithmetic that work, don’t contradict each other, and can answer all kinds of questions with numbers? Well, there are problems with numbers (really strange problems, granted) that our arithmetic cannot answer. And if you try to fix your system so that it can answer those problems, you’ll have issues with other problems. There’s no way to repair your system so that it stays complete and answers all problems.

If this sounds disturbing to you (math doesn’t work?!?!), you’re not alone. Lots of mathematicians were upset by this. They thought, as lots of us do, that math is supposed to be logical. It’s supposed to give us the answers we need. We’re supposed to be able to rely on it. Gödel arrived at this theorem by playing with paradoxes, or statements that self-contradict. (Such as, “Today is opposite day.”) The statement that he came up with really rocked the world of math.

If you’d like to learn more about Gödel and his disturbing theorem, listen to this podcast episode from Radiolab. It talks about Gödel’s life and what his theorem meant for math, with an appearance by everyone’s favorite mathematician, Steve Strogatz!

Gödel’s confusing theorem is only one in a long string of crazy, confusing math paradoxes. Another of my favorites is the Barber Paradox, which mathematician Bertrand Russell came up with. Here it is, in dry-humor video form:

If you like that paradox, you’ll probably also like the Pinocchio Paradox— which was developed by 11-year-old Veronique Eldridge-Smith:

This video comes from the YouTube channel, SpikedMathGames. I suggest you check it out!

Finally, I thought it would be nice to close off this loopy Math Munch post with a loop back to podcasts– and a link to a very large archive of math podcasts called Math Factor. Math Factor is a podcast produced out of the University of Arkansas about all kinds of interesting math. They even have an episode about the topic of this week’s Math Munch! Give it a listen.

Have a terrible opposite day, and bon appetit!

# Functionized Photos, Projective Games, and Traffic

Welcome to this week’s Math Munch!

Have you ever looked in a distorted mirror– one that stretched and squeezed your face so that you looked very, very silly? If you like that, check out this program called the Function Explorer that distorts your picture according to different functions!

My cat under the “fraction” function

To use the program, you’ll have to turn on your webcam. Then, select one of the functions listed– maybe similarity, log, or fraction. Then, watch as the image in front of your webcam twists, expands, and repeats as the function distorts the picture!

What’s going on here? The program treats your picture like it’s on something called the complex plane— which is kind of like the regular two-dimensional plane we’re used to, except that some of the numbers multiply strangely. One of the dimensions on the complex plane is made of regular, normal numbers– which, in this situation, are called the “real numbers”– while the other dimension is made of different numbers, called “imaginary numbers.” These are the numbers that do weird things when you multiply them together. Maybe you’ve heard that you can’t take the square-root of a negative number. Well, on the complex plane you can. And when you do, you get an imaginary number!

Windows, under 1/z

If you’re curious about these crazy creatures called imaginary numbers and how they work to make images go wild on the complex plane, I recommend you check out this site. It gives a great interactive explanation of imaginary numbers (and teaches you about fractals, too!). But I also wouldn’t blame you if you wanted to spend a few hours holding things in front of your webcam and seeing what happens to them under different function transformations!

Gummy bears! Which function did this?

Meet Donna

Next up, I’d like to share a fun collection of games with you. They’re all made by mathematician Donna Dietz, and they all have to do with a particular kind of math that I find very interesting– projective geometry! You can still enjoy the games even if you know nothing about projective geometry (and you might learn something at the same time).

The rules are pretty simple: Donna gives you a bunch of cards with symbols on them. For example, in the version shown here, you get 13 cards with 4 symbols on them each. There are a bunch of different symbols. Your task is to pick four cards to discard and arrange the remaining nine so that the cards in each row, column, and diagonal share exactly one symbol.

Donna’s projective geometry games page has links to lots more games (if you think the game with cards in three rows and columns is too easy, try one with five) and information about them.

“What does this have to do with geometry?” you might be wondering. These games show a very important property of points and lines in projective geometry. In regular geometry (which you could also call Euclidean geometry), you can have two lines that don’t share any points– meaning that they’d be parallel. But this isn’t possible in projective geometry. All pairs of lines share exactly one point. How is this related to Donna’s games? If lines are rows, columns, and diagonals of cards, and points the symbols on them…

If you’d like to learn more about how and why Donna developed these games, check out this page!

Finally, I’ve been driving a lot lately. I live in the Bay Area, and there is SO MUCH TRAFFIC AAAAAAAA!!! I went searching for solutions, and I came across this great video by our friend CGP Grey (who also made these great videos about voting theory). There’s a lot of math going on here, even if it isn’t immediately apparent. Can you find the math? (Oh, and can you stop causing traffic jams? Thanks.)

Don’t Math Munch and drive, and bon appetit!