In the last two months, I’ve become fascinated with clocks and automatons. My family never owned a mechanical clock, but I had an aunt with a musical cuckoo clock, and a grandfather clock that showed the phases of the moon. I wondered what made the pendulum keep swinging (was it magnets or batteries?), and what […]

The book cover for the book Paul and I wrote is now available on Amazon, and here’s what it look like. Here’s the Amazon listing, should you care to pre-order 1 or 2 hundred copies… :) UPDATE: Can’t wait for the book? You can get early access to an online edition using O’Reilly’s new Rough […]

Eduyng Castano writes to me about a Sudoku solving technique he has discovered. Here is his paper describing what he calls Golden Chains (pdf). The technique is a generalization of XY-Wing that identifies exclusion pairs connected by chains of arbitrary length. It solves many (but not all) of the same puzzles that can be solved […]

LEGO unveiled their next generation robotic system, Mindstorms NXT at the Consumer Electronics Show this week. As reported in Wired, the kit features a boatload of new features, including a sleeker RCX with a 32-bit CPU and larger LCX, server-style motors, an ultra-sonic sensor (for motion & obstacle detection) and lots of other robot sweetness. […]

An Astounding Test of Skill Tell a friend (it helps if the friend is in the same room…) that you are going to prove that, although you both are relatively good typists, you are the faster one handed typist. To begin the test, tell your friend to put one hand behind her back, and one […]

Puzzle Japan is the puzzle website for Nikoli, a popular puzzle publisher in Japan that popularized sudoku puzzles. Their website offers eight different logic puzzles, including sudoku and kakuro, available in online and printable formats. Many of the puzzles involve building walls or boundaries, an activity reminiscent of the game of Go. One of my […]

Some people begin the new year by pledging to lose weight or quit smoking. My usual pattern is to try to find two or three new obsessions each year. Perhaps it’s more accurate to say that these obsessions find me! This last year, those obsessions included digital photography, photo mosaics and logic puzzles. After 20 […]

I’ve developed a new kind of puzzle which I’m calling a Krypto Kakuro. They combine elements of crossword puzzles, sudoku and cryptograms (or cryptarithms to be precise). Here are some samples for you to try. If you aren’t familiar with kakuro puzzles, I suggest you solve a few of those first, before tackling these puzzles, […]

How krazy do you have to be to fly around the world on a sleigh and jump into a gazillion chimneys? This mosaic portrait of Father Christmas is constructed from Flickr photos matching various christmas-related tags: snowman, wreath, christmas tree, poinsettia, etc. This image was made using techniques I describe in the forthcoming book Flickr […]

If you like my sudoku puzzles, you’re gonna like my new kakuro puzzles. Also called Cross Sums, these puzzles are like a cross between a Sudoku and a crossword puzzle. I’ve been working on some software that generates these puzzles, and have published a set of them here at Krazydad. Each file contains 20 puzzles, […]