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Penrose Puzzle: Area 51

July 11th, 2012

This Penrose Slitherlink puzzle is inspired by David Millar’s “Area 51″ puzzles, which you can find at The Griddle. The puzzle works like a regular Slitherlink puzzle, but with a few twists: The aliens must be kept inside the fence. The cacti must be kept outside the fence. The white circles indicate a straight line crossing.

Special thanks to David Millar, who drew the cacti and aliens.

Print the PDF

June Processing Workshops

June 4th, 2012

This month, I’ll be teaching two Processing workshops at CRASHspace, the awesome hacker space in Los Angeles. You can sign up for these classes in the CRASHspace store. This is a fundraiser for CRASHspace: all proceeds will go towards paying the rent and such. Each class is 4 hours long, and costs $60 ($40 for CRASHspace members).

Processing 101
Saturday June 16th, 1pm – 5pm

An introduction to the Processing language and development environment. Processing is an open-source language and development environment which is popular with designers, artists, and DIYers. It’s a great language for learning computer programming because of its simplicity and immediate visual rewards. You can use Processing to build a sketchbook of reusable code snippets for future projects.

This class will cover installation and introduce graphic programming techniques in Processing.

Students will learn

  • Basic vector drawing and color manipulation in Processing.
  • How to get images onto the screen.
  • How to effectively use randomness.
  • How to make an animated logo
  • How to make an animated particle system.

Flight Patterns by Aaron Koblin, © 2006
Data+Art in Processing
Saturday June 23rd, 1pm – 5pm

An introduction to using real-world data as an artistic medium in Processing. In this class, students will work with a variety of real-world data sources, and use this data to produce motion graphics, still images or music. The data used in the class includes

  • USGS earthquake records
  • An Astronomical database
  • English Literature
  • Twitter or other web services

Students will learn a variety of methods to map and render this data, including

  • How to control an animated image using multiple datapoints.
  • How to render maps and position items on a globe.
  • How to produce musical events from non-musical data.
  • Steganography – embed secret messages into images or music.

For both classes, students will need a Windows, Macintosh or Linux laptop. If you are very new to Processing, I suggest taking the first class before taking the second.

Chess Music at Handmade Music L.A. #3

May 6th, 2012

Next Saturday, I’ll demonstrate my musical chess system at the 3rd Annual Handmade Music L.A., at CRASH Space in Culver City.

There will be a number of other tinkerer/musicians there as well, showing innovative pieces of homemade music technology, including circuit bending, noisy circuits, repurposed video-games machines, and amplified motors. Hope you can join us! The event is Saturday May 12th, from 8pm until late. It’s free, although a 5$ donation to CRASH Space is suggested.

More Info

Solve Krazydad puzzles on an IPad with UPAD

April 16th, 2012

Lately, I’ve been solving Krazydad puzzles on an iPad, using my finger, or a stylus, rather than printing them out and solving with a pencil.

My iPad app of choice for printable puzzles is UPAD, a great little drawing app that works well with PDF files. It is available in both free and paid versions. The paid version, which I use, is $4.99. The Lite version limits the number of puzzles you can store to 5.

Using UPAD, I can store a collection of PDFs on my iPad, and draw on the individual pages using a variety of colors and pen sizes. There is also a highlighter, which is great for marking cells in Slitherlink puzzles. The Undo/Redo function makes it easy to try risky strategies and correct my mistakes. The different colors are great for more advanced Sudoku strategies.

To load a puzzle into UPAD, just visit the Krazydad website (or any other website which offers PDF puzzles, such as The Griddle) in the web browser on your iPad. Click on the puzzle book you wish to start solving. When the puzzle loads, a button will be available on the upper right that says “Open in UPAD”. Click this button. The UPAD app will launch and load the puzzle file. Then you can start drawing on the puzzle pages.

You only need to import the puzzle file once. Later, when you re-launch UPAD, all the puzzles you’ve previously opened will still be there, unless you’ve deleted them.

You’ll find it takes a little trial and error to get used to using UPAD, but once you do, it is very rewarding, and it will save you from wasting ink and paper. The first problem you’ll encounter is that the puzzle is small, and your finger is enormous. You can work around this by zooming into the puzzle, using a “pinch out” gesture. For larger puzzles, I find myself zooming in and out quite a lot.

UPAD is even better with a stylus. You’ll find a number of cheap stylus options on Amazon.

Here’s a tip of the hat to David Millar for introducing me to this cool app.

Floret Slitherlink

April 14th, 2012

Here are six new Slitherlink puzzles for you to try. This puzzle is based on Floret Pentagonal Tiling, which was suggested to me by Danny Sichel. The additional clue styles (ampersand and dollar sign) were inspired by David Millar’s excellent “Area 51″ puzzles, from The Griddle.

Floret Slitherlink

Fill in some of the dotted line segments to form a meandering path that forms a single loop. The path does not cross itself, branch, or touch itself at corners. The numbers indicate how many line segments surround each cell. Empty cells may be surrounded by any number of line segments.

A dollar sign ($) indicates the cell is inside the loop. An ampersand (&) indicates the cell is outside the loop.

There is one unique solution, and you should be able to find it without guessing. You may find it helpful to mark segments that cannot be filled in. It also helps to highlight cells which are inside the loop.

Letters, I get letters

April 5th, 2012

Dear Krazydad,
My husband just started doing KenKen and really loves it. I have a question for you as most of your Inky puzzles seem to have this symbol in them: What does the symbol / mean?


Dear Confused,

The / symbol is used to mean division (as in 12/4 = 3). It means the same thing as รท, the division sign. I used the slash because the division symbol is easily confused with a plus sign at small font sizes.


I must be dense, but I don’t understand the cheat sheet(candidate cage set)for the Killer Sudoku puzzles. Why are some
numbers in red? What do the exclamation points mean? Please advise!

Dora the Killer

Dear Dora,

The red ones with explanation points mean “all numbers except these ones”. I should fix those, as this is the second letter asking for clarity. :)

I am having trouble getting to your puzzles to print. Every time i try I get a message that Internet Explorer has stopped working. Any comments or suggestions?

Dear Printless,

It sounds like the Adobe Reader plug-in, which IE uses to view and print PDF files, has stopped working.

I recommend that you reinstall Adobe reader. You can get a new copy on Adobe’s website (link).

If you can’t get Adobe Reader to stop crashing your browser, a workaround is to download the puzzles to your desktop, and view/print them there. To download a puzzle, right-click the link (likely the same link that is crashing your browser) and select Save-As from the menu that appears. Double-click on the PDF file that you’ve downloaded and print it when it opens.

Good luck, and let me know if you run into more trouble.

Hi Jim,

I wanted to contribute my praise and thanks for your site.

I work as the librarian in a maximum security federal prison in Canada, and there are many offenders here who have received printed out puzzles since I found your site. They are unable to pay for things like this, so finding Krazydad has been a Godsend.

There are several ways this helps here. First of all, decreasing idleness is an important contributing factor to prison security. I often provide them especially to men who are in segregation and may not have regular access to other humans, books, or television. If they are occupied, they can put in time without causing needless disruptions.
Secondly, for our older offenders, keeping the mind active (thereby contributing to overall health) can be very challenging in this setting, and puzzles help out a lot.

So thanks again, especially for providing your service free of charge to those who can’t pay, and keep up the good work!

Shh the Librarian

Dear Shh,

Wow, what a nice letter! I’ve gotten a few letters from spouses of inmates, but this is the first from someone working on the inside. I wish there was a way I could get more puzzles out to inmates in a more organized way. If you have any ideas, let me know.

Lego Mindstorms used to make artificial bones

March 13th, 2012

Wonderment Rank

March 1st, 2012

The other day, I idly wondered about the band-aids or surgical tape visible on Michael Jackson’s fingertips. I took out my smartphone, and started typing in the query “why did michael jackson wear bandages on his fingers“. As I typed the first few words, the search box filled with a slew of Google search suggestions:

Why did michael jackson die?
Why did michael jackson turn white?
Why did michael jackson change his nose?
Why did michael jackson bleach his skin?

It occurred to me that the number of questions like these would be higher for some celebrities, like Michael Jackson, than for others. I decided to try to measure this, so I wrote a little script that measures the “Wonderment Rank” of various people and things.

You give the script a word or phrase, such as “michael jackson” or “kittens”, and it constructs a series of partial search queries:

why did ____
why does ____
why do ____
how come ___
why didn’t ___
why doesn’t ___
why don’t ___

It then counts the total amount of Google search traffic for all these partial phrases, using this undocumented API and reports the results. Wonderment Rank is reported as a single number, which represents millions of searches.

For the record, here is the Wonderment Rank of Michael Jackson, along with a few other celebrities.

whitney houston 2393.62
steve jobs 1112.22
the beatles 1344.29
lady gaga 1095.69
michael jackson 960.31
justin bieber 621.47
angelina 176.97
jack black 119.30
ben franklin 50.82
davy jones 0.40
sacha baron cohen 0

As you can see, the recently deceased tend to score highly (except for Davy Jones). Some celebrities, such as Sacha Baron Cohen, score nary a blip, which leads me to believe that Google has some kind of arbitrary cutoff in reporting results.

The results (and my methodology) suggest that Wonderment Rank is strongly correlated to overall search popularity. It’s not the same thing, however. Consider kittens. Google Trends reveals that “kittens” have roughly twice the search traffic of “jack black”, but kittens merit a relatively low wonderment rank of 21. Yes they are cute and playful, but not exactly mysterious.

kittens 21.80
puppies 134.74

Celebrities and kittens aren’t the only things people wonder about. They also wonder about politics.

republicans 2286.87
democrats 1277.82
politicians 1612.73
romney 4374.55
ron paul 2320.61
gingrich 2110.03
obama 1379.45
santorum 733.16

And we all wonder about existential questions. We wonder about the motivations of God, and about Jesus. We wonder about life, death, taxes, and why do birds suddenly appear?

life 9238.58
jesus 6199.19
god 4560.73
death 2247.20
tax,taxes 1813.87
birds 1145.98

Men wonder about women. Women wonder about men, but not to the same degree. As a man, I expected women to score more highly, but apparently, I was wrong:

men 10774.63
women 6900.09

Parents wonder about their kids:

kids 12749.90
boys 10196.22
girls 8862.12
babies 3068.72

And people wonder about anybody, anyone, someone, and nobody:

no one 14135.55
anyone 11386.79
nobody 2663.10
anybody 4845.46
someone 3743.05

For the nerds in the audience, here is the perl script I wrote to measure wonderment rank, and here is a version I made in ruby.

Over the next few days, I’ll post a few more results.

UPDATE: A few days after I wrote this, Google stopped providing search-query counts in their suggest API. This change makes this metric much less precise, although the API can still be used to detect some level of interest.

EDIT: I corrected the spelling of Sacha Baron Cohen – thanks Clive!


February 13th, 2012

One of the wonderful mathematical notebook videos from Vi Hart. This one contains a curious puzzle – can you identify Wau?

Sheet Music for “Being There” soundtrack

February 2nd, 2012

I first saw the Peter Sellers movie “Being There” in 1979, and fell in love with Johnny Mandel’s two piano pieces on the soundtrack. For years, pre Internet, I didn’t know what the pieces were. Although they sounded like classical piano music, they are not credited in the film, there is no soundtrack album, nor sheet music available. Finally, some time in the 90s, I heard Erik Satie’s Gnossiennes #4 and #5, which they are derived from, and recognized them immediately. I learned the Satie pieces, but then when I saw the movie again, I realized that Mandel’s versions of the Gnossiennes differ significantly from the originals. Mandel’s version of Gnossienne #4, “The Room Upstairs” can be heard in this clip on YouTube, starting around 2:40.

While Satie’s Gnossienne #4 maintains an ambient glasslike stasis throughout, Mandel’s “The Room Upstairs” contains some more straightforward harmonies, giving it a stronger emotional impact, suitable for a film score. Mandel’s version of Gnossienne #5, “Goodbye Louise”, which you can here in the end credits, introduces some Joplin-like motifs that aren’t present in the original. At the risk of offending purists, I think Mandel’s melody lines are more appealing, as well.

I eventually tracked down a decent MIDI arrangement of “The Room Upstairs”, by an unknown arranger, here. There is also a good recording of the two piano pieces from the film on Stephen Edward’s album, Piano Music from the Movies, which also contains some other great piano recordings of obscure film pieces, all available as MP3s from Amazon.

Using these source materials, I was finally able to make sheet music versions of the “The Room Upstairs”, and “Goodbye Louise”, which I thought I’d share. I haven’t completely finished marking all the phrasing, but there’s enough here for a competent pianist to work with.

Being There: The Room Upstairs, Johnny Mandel, Sheet Music

Being There: Goodbye Louise, Johnny Mandel, Sheet Music