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Chessville
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Chessudoku Reviewed by Rick Kennedy
Admit it, Chessplayer – in between your over-the-board chess challenges and online blitz battles, you’ve been known to take a look at the occasional “mate-in-3” problem or endgame study. No cause for worry there, you tell yourself: it improves your game. Truth be told, you’ve even been caught paging through Peter Wong’s Parallel Strategy: 156 Chess Compositions – enjoying the unusual ones in there really won’t affect your ability to play the King’s Gambit or the Najdorf Sicilian. Besides, didn’t chess psychologist Amatzia Avni opine "Rich knowledge and considerable experience increase the probability that the right idea will emerge at the right time"? But lately you’ve found yourself dabbling in those new numbers-in-the-squares problems called sudoku. Reassuring yourself that scientists believe such cognitive challenges will help one maintain mental clarity and put off the brain-numbing effects of Alzheimer’s still doesn’t relieve your guilty feeling that, somehow, you’ve strayed from your true love, Caissa… Matthew Skala – Canadian graduate student, computer and astrology maven, egghead (literally and figuratively), creator of the wicked online comic “Bonobo Conspiracy” (how many times have you seen Gödel’s Incompleteness Theorem used as a punch line?) – to the rescue! His Chessudoku, from Lulu (a publish-on-demand house, www.lulu.com), available in both paperback and downloadable PDF file forms, is an interesting and enjoyable blend of chess, sudoku, and story-telling in the style of Raymond Smullyan’s The Chess Mysteries of Sherlock Holmes and The Chess Mysteries of the Arabian Knights. The settings for each of the 351 puzzles are primarily the castles of the White or Black King, or, more specifically, their Soduko Gardens. (Later challenges involving number placement and an imaginary chess piece called the Amazon – which can move like either a Rook, Bishop or Knight – take place in Amazonia.) Each Garden is laid out in a 9x9 grid of squares, further sub-divided into nine “blocks” of nine squares. Sometimes these blocks are 3x3 squares themselves, sometimes they look like gerrymandered shapes, depending on the nature of puzzle. The puzzles were created by a combination of human and computer effort, the author using “a customized solver written using the CHR constraint logic system on top of SWI-Prolog”. (For that matter, the background image on the books cover is “Volterra-Lotka fractal generated by xfractint, using the atan and tdis colouring options.” I knew that…) Each is rated according to difficulty, with a scores under 200 being comparatively easy, and ones over 300 being increasingly harder. In an early puzzle (rated 169) the challenge is to place the numbers 1 through 8, plus a White Knight, in each 3x3 square, so that when completed, all the vertical columns of the Garden have the numbers 1 through 8 (plus a Knight) only once, and all the horizontal ranks, likewise. An additional constraint is that Knights cannot be placed so that any one is in a position where it can capture another. (You can check out http://www.lulu.com/browse/preview.php?fCID=325086 for an example.) Later puzzles involve Black Knights (who must be placed to support one another), Kings and Queens (who sometimes have jealousy issues), Amazons and Pawns, each with their own placement rules. The introductory stories give clear explanations on how the challenges are set up, and what the solver needs to do. Skala believes, like Sherlock Holmes, that all can be solved logically. (Puzzle #300, on page 175, involves a Black King and a Black Amazon and is a real, if you’ll excuse me, lulu, rated at 951…)
So, if you’ve caught the sudoko wave, you should give Chessudoku a
try. You don’t need a portable chess board for it, but unless you’re a
Grandmaster problem-solver you might want to work with a pencil, not a pen.
(That tip is for you, “Kennedy
Kid” Jon.) I have no idea how the author came up with the
price of $13.32 for the paperback version, but at $3.50 for the PDF download
(which can be read with the readily available free Adobe Reader) that’s like
a penny per puzzle. Sudoku, for sure, but Chess sudoku.
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