# The World Cup Group Stage, Math at First Sight, and Geokone

Welcome to this week’s Math Munch! We’ve got some World Cup math from a tremendous recreational mathematics blog and a new mathematical art tool. Get ready to dig in!

Brazuca: The 2014 World Cup Ball

I’ve been meaning to share the really fantastic Puzzle Zapper Blog, because it’s so full of cool ideas, but the timing is perfect, because IT’S WORLD CUP TIME!!! and the most recent post is about the math of the world cup group stage! It’s called “World Cup Group Scores, and “Birthday Paradox” Paradoxes,” and I hope you’ll give it a read. (For some background on the Birthday Paradox, watch this Numberphile video called 23 and Football Birthdays.)

The thing that got me interested in the article was actually just this chart. I think it’s really cool, probably because I always find myself two games through the group stage, thinking of all the possible outcomes. If you do nothing else with this article, come to understand this chart. I was kind of surprised how many possible outcomes there are.

All Possible World Cup Group Stage Results

Long story short (though you should read the long story), there’s about a 40% chance that all 8 world cup groups will finish with different scores.

Alexandre Owen Muñiz, Author of Puzzle Zapper.  (click for an interview video about Alexandre’s interactive fiction)

Puzzle Zapper is the recreational mathematics blog of Alexandre Owen Muñiz. You can also find much of his work on his Math at First Sight site. He has a lot of great stuff with polyominoes and other polyforms (see the nifty pics below). Alexandre is also a writer of interactive fiction, which is basically a sort of text-based video game. Click on Alexandre’s picture to learn more.

The complete set of “hinged tetrominoes”

A lovely, symmetric family portrait of the “hinged tetriamonds”

I hope you’ll poke around Alexandre’s site and find something interesting to learn about.

For our last item this week, I’ve decided to share a new mathematical art tool called Geokone. This app is a recursive, parametric drawing tool. It’s recursive, because it is based on a repeating structure, similar to those exhibited by fractals, and it’s parametric, because the tool bar on the right has a number of parameters that you can change to alter the image. The artistic creation is in playing with the parameter values and deciding what is pleasing. Below are some examples I created and exported.

I have to say, Geokone is not the easiest thing in the world to use, but if you spend some time playing AND thinking, you can almost certainly figure some things out! As always, if you make something cool, please email it to us!

##### Now go create something!  Click to go to Geokone.net.

I hope you find something tasty this week. Bon appetit!

# Halving Fun, Self-Tiling Tile Sets, and Doodal

Welcome to this week’s Math Munch!

Print out two copies of this pattern, cut them out, and fold each along the dotted lines, making two identical solids. Then fit these two pieces together to make a regular tetrahedron.

Our first bit of fun comes from a blog called Futility Closet (previously featured). It’s a neat little cut-and-fold puzzle. The shape to the right can be folded up to make a solid with 5 sides. Two of them can be combined to make a solid with only 4 sides, the regular tetrahedron. If you’d like, you can use our printable version, which has two copies on one sheet.

What do you know, I also found our second item on Futility Closet! Check out the cool family of tiles below. What do you notice?

A family of self-tiling tiles

Did you notice that the four shapes in the middle are the same as the four larger shapes on the outside? The four tiles in the middle can combine to create larger versions of themselves! They can make any and all of the original four!!

Recreational Mathematician, Lee Sallows

Naturally, I was reminded of the geomagic squares we featured a while back (more at geomagicsquares.com), and then I came to realize they were designed by the same person, the incredible Lee Sallows! (For another amazing one of Lee Sallows creations, give this incredible sentence a read.) You can also visit his website, leesallows.com.

A family of 6 self-tiling tiles

For more self-tiling tiles (and there are many more amazing sets) click here. I have to point out one more in particular. It’s like a geomagic square, but not quite. It’s just wonderful. Maybe it ought to be called a “self-tiling latin square.”

And for a final item this week, we have a powerful drawing tool. It’s a website that reminds me a lot of recursive drawing, but it’s got a different feel and some excellent features. It’s called Doodal. Basically, whatever you draw inside of the big orange frame will be copied into the blue frames.  So if there’s a blue frame inside of an orange frame, that blue frame gets copied inside of itself… and then that copy gets copied… and then that copy…!!!

To start, why don’t you check out this amazing video showing off some examples of what you can create. They go fast, so it’s not really a tutorial, but it made me want to figure more things out about the program.

I like to use the “delete frame” button to start off with just one frame. It’s easier for me to understand if its simpler. You can also find instructions on the bottom. Oh, and try using the shift key when you move the blue frames. If you make something you like, save it, email it to us, and we’ll add it to our readers’ gallery.

##### Start doodaling!

Make something you love. Bon appetit!

A fractal Math Munch Doodal

# Havel-Hakimi, Temari, and more GIFS

Welcome to this week’s Math Munch!  We’ve got another great game for you, a followup with Temari artist Carolyn Yackel, and some mind-blowing math gifs.

Havel-Hakimi

First up, a nice little graph theory game created by Jacopo Notarstefano.  The game is about whether or not sets of numbers meet the conditions for being “graphical.”  Maybe the best way to understand what that means is to start playing.  If you can beat a level, then the starting number set is graphical.  Go play Havel-Hakimi.

In 1960, mathematicians Paul Erdös and Tibor Gallai proved a theorem about what number sets were graphical.  The name of the game refers to an algorithm you can use to solve the game.  You might figure it out just by playing the game, but here’s a (pretty dry) video explaining how the Havel-Hakimi algorithm works.

Jacopo’s website has a few other nice projects.  See if you can figure out Who Killed the Duke of Densmore, or try Four-Coloring the Dodecahedron.

Carolyn Yackel

Up next, remember Carolyn Yackel.  We wrote about Carolyn and her mathematical art a while back.  Well we finally got around to doing a little Q&A.  Give it a read to learn about Carolyn and her love of math.

Carolyn’s art (which can be seen here) is called temari, the japanese art of embroidered spheres. Since our post about Carolyn we found out that a now 93-year old grandmother posted a lifetime of temari on flickr.  These beautiful objects have symmetry that mimic various polyhedra, which I just love.  Read Carolyn’s Q&A to hear about how you make them.

A Grandmother’s Temari Work

Finally, a while back we shared some mathematical gif animations created by Bees and Bombs.  It’s time once again to look at some amazing animations.  This time they’re created by David Pope.  Here’s the complete archive of animations.  I’ll post some of my very favorites below, but there are dozens of dozens of good animations. (A dozen dozens is gross!)

Have a great week.  Bon appetit!

## Full gallery of mathematical gifs

 Pyramid Rolling Prisms Sphere

Spinning Octahedra

# 2048, 2584, and variations on a theme

Welcome to this week’s Math Munch! It’s a week of mathematical games, including a devilish little game and variations on the theme.

2048

First up, check out this simple little game called 2048. Really, you must go try that game before reading on.

Gabriele Cirulli

2048 was created by Gabriele Cirulli, a 20-year old who lives in northern Italy. He was inspired by a couple of very similar games called 1024 and threes, and he wanted to see if he could code a game from scratch. Nice work, Gabriele! (Stay tuned for a Q&A with Gabriele. Coming soon.)

The first time I played, I thought randomly moving the pieces around would work as well as anything, but wow was I wrong. Give it a try and see how far you get. Now watch how this AI (artificial intelligence) computer program plays 2048. You’ll probably notice some patterns that will help you play on your own.

A beautiful chain of powers of two.  Can you solve from here?

Did you notice that the smallest tiles are 2’s, and you can only combine matching tiles to create their double? This makes all of the tile values powers of two! (e.g. 2048=2^11) These are the place values for the binary number system! (Did you see our recent post binary?) This has something to do with the long chains that are so useful in solving the game. It’s just like this moment in the marble calculator video.

4, a silly, but interesting little variation

If you’re finding 2048 a bit too hard, here’s an easier version.  It’s called 4. It’s a little silly, but it’s also quite interesting. After you make the 4 tile (tying the world record for fewest moves), click “keep going” and see how far you can get. I’ve never been able to get past the 16 tile. Can anyone make the 32? What’s the largest possible tile that can be made in the original 2048 game? Amazingly, someone actually made a 16384 tile!!!

2584, the Fibonacci version of 2048

Silly versions aside, there are lots and lots of ways you could alter 2048 to make an interesting game. I wondered about a version where three tiles combined instead of two, but I couldn’t quite figure out how it would work. Can you? (See below.) When I thought about different types of numbers that could combine, I thought of the perfect thing. The Fibonacci numbers!!! 1, 1, 2, 3, 5, 8, 13, 21, … The great thing is that someone else had the same idea, and the game already exists! Take some time now to play 2584, the Fibonacci version of 2048.

2048 and 2584 might seem like very similar games at first, (they’re only 536 apart), but there are some really sneaky and important differences. In the Fibonacci version, a tile doesn’t combine with itself. It has two different kinds of tiles it can match with. I think this makes the game a little easier, but the website says 2584 is more difficult than the original. What do you think?

I have a few more 2048 variations to share with you, as if you didn’t have enough already. These are my favorites:

I hope you dig into some of these games this week. Really think and analyze. If you come up with clever strategies or methods to solve these puzzles, please let us know in the comments. Have a great week, and bon appetit!

# Byrne’s Euclid, Helen Friel, and PolygonJazz

Welcome to this week’s Math Munch! We’ve got geometry galore, starting with a series of historical math diagrams and a color update to Euclid’s Elements. Then it’s onto modern day paper artist Helen Friel, and finally a nifty new app that makes music from polygons. Let’s get into it.

Euclid’s “Elements” was written around 300BC. It was the first great compilation of geometric knowledge, broken into 13 books, and it is one of the most influential books of all time. Euclid’s proof of the Pythagorean Theorem may be his most famous proof from the book (and all of mathematics for that matter), and in the pictures below you can see three diagrams of the proof, spanning seven centuries.

 Persian mathematician Nasir al-Din al-Tusi‘s 13th century arabic translation of Euclid’s proof. A late 14th century English manuscript of Euclid’s “Elements.”

The idea in each picture is that the area of the top two squares adds up exactly to the area of the bottom square. In the picture below, we see the big square broken up into blue and yellow pieces, whose areas are the same as the squares above them.

Oliver Byrne’s 1847 color edition.  Click the image for the full proof of the Pythagorean Theorem as presented by Oliver Byrne in 1847.

This color version comes from Oliver Byrne’s 1847 edition, “The First Six Books of the Elements of Euclid, with Coloured Diagrams and Symbols.” (completely available online). I find the diagrams really beautiful and charming. There’s something extremely modern about them (see De Stijl) though they’re more than 150 years old now. See if you can follow his Oliver Byrne’s version of Euclid’s proof. It’s quite short.

Paper Engineer Helen Friel

“They’re an absolutely beautiful piece of work and far ahead of their time,” said paper engineer Helen Friel. Helen lives in London, and and as part of a charity project, she designed paper sculptures of Oliver Byrne’s diagrams.

In an interview, she explained, “It’s a more visual and intriguing way to describe the geometry. I love anything that simplifies. I find it very appealing!” In the interview, Helen also talks a little about her attraction to math. “There’s order in straight lines and geometry. Although my job is creative, I use as much logical progression as possible in my work.”

It’s also cool to see Helen’s work side by side with Oliver Byrne‘s, so click for that.

Click to send us a pic.  Yes, that is a paper camera Helen made.

Perhaps the best part in all of this, though, is that you can download Helen’s Pythagaorean Theorem model and make your own! There are plain white version as well as color. If you end up making one, definitely email us a picture, and we’ll show it off here on Math Munch.

Oh, and here’s a quick video documenting the many versions Helen decided not to use.  So cool.

Now, on to our final bite.
Recently, John Miller sent me an email showing off his new iPad app called PolygonJazz. In the app, you control the starting direction for a ball inside a polygon. Once you start it moving, the ball bounces off the walls, making a sound every time it hits a side. Check out the video below. I noticed something about the speed of the ball. Can you spot it? (PolygonJazz is available for \$0.99 on the iTunes store.)

Speaking of bouncing around, here‘s a previous Math Munch featuring some billiards, and here‘s another bouncy post that features one of my favorite juggling routines. Michael Moschen built a gigantic equilateral triangle and juggles silicon balls inside and off of it. As with the app, Michael is utilizing the sound and geometry of the collisions to make something beautiful. It’s quite mesmerizing.

Have a bouncy week, and bon appetit!

# Platonic Terrariums, Geometric Decor, and Multiplying Polyhedra

Welcome to this week’s Math Munch! We’ve got some beautiful geometric objects meant to house a plant or decorate your home, as well as a really clever kind of “multiplication chart” relating the Platonic solids to each other.

Icosahedron Terrarium

First up, let’s take a look at some gorgeous glass terrarium models of the Platonic solids. We don’t usually share products here on Math Munch, because we want to make sure you can enjoy the math for free, but these are so beautiful I just had to show you. I’m a sucker for spherical symmetry!

The Turning Triangles Terrarium actually sits on my mantle at home. It’s 20 pieces of triangular glass (with one hinged pane) coming together to make an icosahedron home for a little plant.

Octahedron Terrariums

Above you can see a spread of octahedron terrariums, which will have to be my next purchase. Does \$29 seem like a lot for one of those? I was kind of shocked to  see prices for other ones that are about 4 times that much. Take a look at the dodecahedron and cube terrariums below. They’re over \$100 each, but man are they cool!?

Dodecahedron and Cube Terrariums

I love how they stood the cube up on its corner. Did you ever think about how cutting off the corner of a cube creates a little triangle?

Speaking of cutting off corners, that’s called “truncation.” I bet you never realized the soccer ball pattern is a truncated icosahedron. Well it is! And West Elm is selling a pair of really beautiful truncated polyhedra made of Capiz shells. Below are the corner-cut versions of the icosahedron and dodecahedron.

Capiz Shell Truncated Polyhedra

OK, just a couple more. First, I love the blue and white of these two shapes. One correction: the seller calls them an “octahedron”, but they have more than 8 faces. These are actually cuboctahedra. (Can you figure out how many sides they do have?)

Metal Icosidodecahedra

And lastly, the really cool, metal rhombicosidodecahedron. This is the shape that is used for the Zome construction kit. Check out this video showing a project we did last year. In short, we made a really big version of this out of lots of little ones.

If you end up buying one of these decorative sculptures, let us know. We’d love to see a picture of it in your house.

Finally, this is a really incredible image I found on Pinterest. Can you tell what’s going?

A Platonic solid “multiplication” chart

It’s set up like a multiplication chart, with the Platonic solids along the top and left edges. In the middle, we get a picture showing how the two shapes might be related to each other. I could (and have) stared at this for hours!

A1

In the A1 position, for example, we have a picture showing that the tetrahedron is the dual of the tetrahedron. That means, when you connect the centers of the faces on the tetrahedron, you get another tetrahedron!

 B3 E4 B2 B1

C3

B3 shows that the octhahedron is the dual of the cube. E4 shows that the icosahedron is the dual of the dodecahedron. B2 appears to be a hypercube, and B1 shows the way that a tetrahedron can be made by connecting alternating corners of a cube. It’s a fascinating chart, and I hope you’ll take some time to check it out. Can you figure out what’s going on in C3?

I would love to know where this image came from, but I can’t find anything about it. If you know anything about the origin of the chart, please let us know.

Well that’s it. I hope you found something juicy. Bon appetit!

# Jim Loy, Exploding Dots, and an Advent Calendar

Jim Loy

Welcome to this week’s Math Munch! We’ve got a mathematical advent calendar for you, two new puzzle pages, and a whole course’s worth of videos and problems to think about. Let’s get into it.

Up first, if you like you can read all about Jim Loy (and just about anything else) on his enormous website. The thing I want to share with you are Jim’s puzzle pages. You could pull out some toothpicks or spaghetti and try these matchstick puzzles, or perhaps you want to give his maze a try. Or maybe you just want to learn about the pig pen cipher, a kind of code.

 Matchstick Puzzles Jim’s Maze Pig Pen Cipher

Up next, some math in the holiday spirit. Plus Magazine has a nice little advent calendar going on again this year. They’re counting down to Christmas by posting their “favourite bits of maths” – a new post each day. On the website you can see preview pictures for each day, which has me pretty excited. What could #7 be? What is going on in 18?! Check out #2. It’s a nice little explanation of a classic math story about Achilles and the tortoise. (Zeno’s Paradox). Plus Magazine is a great website in general, but you have to be prepared to do some reading. According to their about page,

Plus is an internet magazine which aims to introduce readers to the beauty and the practical applications of mathematics. A lot of people don’t have a very clear idea what “real” maths consists of, and often they don’t realise how many things they take for granted only work because of a generous helping of it.”

BONUS:  Take a look at the Plus Mag puzzle page!

Finally, you might remember James Tanton for his partition videos. Well, he just released a really cool series of videos and math activities that’s completely free and online. It’s kind of an entire math course (but it’s unlike any course you’ve  seen before), and it’s called “Exploding Dots.” As James says in the intro video above, this is his favorite topic of all time! The course is broken up into 4 lessons, with a handful of videos in each lesson, and there are some really nice questions to think about. I’ve studied math for many years at this point, but there were lots of things that surprised me.

If you’re ready to dig in, here’s a link to Lesson 1.1 Base Machines.

Have a great week, and bon appetit!