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## Twin Sudoku

Without instructions, I’m showing (by example) how to do these two interrelated and yet independent Sudoku puzzles. Thanks to Henry Kwok for the idea, although his example maps two sets of digits, which may be more difficult (confusing).

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## 2nd World Sudoku Championship

This year, From March 28 Through April 1, 2007, The 2007 World Sudoku Championship will take place in Prague, Czech Republic. This championship is sponsored by the World Puzzle Federation. The World Sudoku Championship competitions consist of individual as well as National Team competitions.

It seems like it would be an interesting way to play along (nearly concurrently) if the puzzles are published on that site during the competition. I’m looking forward to it. I missed the 1st World Sudoku Championship and conference held last March 2006. Twenty-two National Teams were represented there.

By downloading the 2.4 MB pdf file via the Sudoku booklet link, you can see the kinds of Sudoku variants that the contestants were exposed to and can solve separately and check your answers with the solution. The game titles are given in the Schedule page, consistent with the instruction booklet.

It’s an amazing collection of variants. Practicing for speed and correctness must be grueling as much before the matches as during competition play.

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## Flickr Sudoku

A visually interesting mashup of Sudoku and Flickr involving pictures of numbers is shown in Flickr Sudoku. This is an online playable game, (although rendering for the Safari 1.3.2 browser is flawed at the bottom).

Unfortunately, the presentation reminds me of a numerical ransom note. This is not to minimize the great work that went into creating this site. I also like the various (random) Sudoku keyword searches on Google shown at the top. There’s a Time of Day Site called Human Clock that has found and created objects/photos with the correct hour and minute that uses a similar idea.

A more abstract version of the same concept is shown on Becky’s Web where 9 thematically grouped pictures and a blank picture are shown in a playable grid. Like the large varieties of layouts in Mah Jong Solitaire Software Puzzles, the original chinese characters are transformed into various alternative symbol sets.

I believe it is a good idea, when exercising the brain, to expose it to a variety of “settings” or contexts in which puzzle solving logic can be applied. The brain embraces the novelty and adapts to a more flexible solving environment.

Thanks to Webmaster for letting me know about these sites.

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## Sudoku Coloring Puzzle

Ivars Peterson, written about last week here, has announced his departure from Science News and Math Trek Blog for a position as Director of Publications for Journals and Communications at the Mathematical Association of America (MAA). His new blog, due in March 2007, will be called: The Mathematical Tourist.

Within the MAA Online website, Ed Pegg, back in September 2005, surveyed the varieties of Sudoku and showed many actual variants, some of which are regularly published (especially in Japan). It is an excellent article and a testament to Sudoku puzzlers’ low tolerance for boredom.

I especially like the Cubic Sudoku, which contains 2×4 rectangles on the cube faces with 1×8 “bent in the middle” strips that comprise the “rows” and “columns”. I’m an easy mark for 3-D puzzles.

On a Dutch Web site called Sudokube that I roughly translated with the help of babelfish, there is a hybrid of Sudoku and Rubik’s Cube available for sale for only 7.49 Euros per. (It offers a reduction in price to 5 Euros on its home page.)

This is what I find ironic: the original Rubik’s Cube consisted of 6 colors that get ultimately arranged to have one color per face of the cube. Sudokube has produced a rubik’s-like cube with the digits 1 through 9, in order, on each face, when solved.

Whereas, in my Sudoku Coloring Boards Cartoon of February 10, 2007, I rendered a Sudoku puzzle into a color mapping and a pattern mapping of the digits 1 through 9 from the original starting numbers. I’ve not seen any instances of this variant anywhere else.

I believe this will be very attractive to people whose visual color sense is advanced and whose number sense has been stifled in early life or atrophied. Since I teach math and feel rather un-visual, does anyone else concur (or not) with this?

How do you go about solving the Sudoku Coloring Puzzle as shown in the Cartoon? It seems to me that using small colored dots to make temporary notes in the boxes is analogous to the small numbers one writes as permissible entries. Do you solve the puzzle quicker or slower than one with numbers?

Obviously, solving this is perfect for the Power SudokuČ white board and colored markers found elsewhere on erasablegames.com. If you lack 9 different solid color markers, you can assign patterns for the missing solid colors instead, although that makes small notes harder to write.