Archive for the 'Puzzles' Category
Tuesday, January 10th, 2012
The science journal Nature reports that a mathematician has proven that it takes 17 clues to make a Sudoku. Gary McGuire of University College Dublin showed this in a proof posted online on January 1st (apparently he wasn’t partying on new year’s eve). This means that sudoku puzzles with 16 or fewer clues do not […]
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Friday, January 6th, 2012
I just found a book in the Kindle bookstore that (incompetently) rips off some of my sudoku puzzles. The book is called “The Most Difficult and Hardest Sudoku Puzzles” and is “copyrighted” by one Johnny Cohen. Here’s the cover: The cover helpfully informs you that the book is a BEST SELLER. Here’s a sample of […]
Posted in Good reads, Jim's Projects, Linkydinks, Puzzles  7 Comments »
Tuesday, December 20th, 2011
At the request of a few persistent (and possibly masochistic) puzzle fans, I’ve added four collections of Hexadecimal Sudoku to the puzzle collection. These are 16 x 16 puzzles that use the 16 hexadecimal digits (0F), instead of the nine digits used in regular Sudoku puzzles. This is a good puzzle to take on your […]
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Thursday, November 24th, 2011
Troubleshooter #4: XYZWing This is part of a series on puzzle solving techniques. If you are stuck on a particular Krazydad puzzle, drop me a note, and I’ll use this space to help you out. Michael wrote in an email: Dad, Good morning and an early happy thanksgiving. I really enjoy your puzzles and I […]
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Friday, November 4th, 2011
One of the most difficult Slitherlink puzzles I publish is the Laves Slitherlink, which you can find in its own collection, as well as in my variety slitherlink collection. I recently helped a reader, Billy, solve one of these monsters, and I thought I’d share the tips here. We explored a handful of advanced solving […]
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Wednesday, September 21st, 2011
This is undoubtedly the coolest wood working project I have ever seen. A wooden desk whose drawers emit pipe organ sounds ranging over an octave. Open the doors to play a particular melody, and a secret compartment opens. The password can be changed by turning wood screws on the wooden pneumatic logic board, shown below. […]
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Thursday, September 8th, 2011
I’m currently working on an interactive Sudoku page (to be followed by other puzzles as well). If you’d like to play with a very early “beta” version of it, you’ll find it here. The page is designed to work in modern web browsers (Safari, Chrome, Firefox 4+, IE 9+), and also works on iPads. A […]
Posted in Jim's Projects, Puzzles  6 Comments »
Monday, August 29th, 2011
This is part of a series on puzzle solving techniques. If you are stuck on a particular Krazydad puzzle, drop me a note, and I’ll use this space to help you out. This is a tough puzzle, book 7, puzzle 7. It was submitted by Stephen, who got stuck after solving 4 numbers, like so: […]
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Wednesday, August 24th, 2011
This is part of a series on puzzle solving techniques. If you are stuck on a particular Krazydad puzzle, drop me a note, and I’ll use this space to help you out. This puzzle is also from Margaret, who got stuck on a Tough puzzle (Tough #4 from book 40). If you’d like to try […]
Posted in Puzzles  Comments Off on Sudoku Troubleshooter #2 – XYWing
Tuesday, August 23rd, 2011
Occasionally, I get mail from fans of the site who need help with a puzzle. I’ve decided to devote the next few blog entries to puzzle solving techniques. If you want help with a particular Krazydad puzzle (especially puzzles that are easier than “Super Tough”), drop me a note, and I’ll troubleshoot your problem too! […]
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