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10 August 2005



Logical rather than mathematical? Sounds like a line too fine for me.



I agree with the first post and would add that logical and mathematical recreations should class in the same place (i.e., 793.74).

I disagree with the other residents of Dewey Manor in that I think Sudoku really counts as a mathematical game, even though it doesn't require players to carry out any mathematical operations. The popular version of Sudoku (i.e., the one described in the 1st 20 Google results) is played using numbers (mathematical symbols). I think of number games as mathematical recreations, and I agree with the LC subject heading (sh85082131) which has Number games as a 450 ref. to Mathematical recreations. To my way of thinking Guardian's Godoku (which doesn't have much literary warrant) is another game: a logical game using letters that should also class in 793.74.

Lastly, it is worth noting that the Wikipedia entry for Sudoku explains the complex mathematics of the game at some length (NP-complete, etc.) and there more than a few websites dedicated to the mathematics of Sudoku; one such site explains, "People addicted to the current Sudoku craze can now log on to a UQ mathematics website to find helpful advice about solving these intriguing puzzles.
UQ Mathematics Professor Anne Street and Associate Professor Diane Donovan have created the website, http://www.maths.uq.edu.au/~dmd/puzzles-and-other.htm

What is that all about?

Giles Martin

LCDennis's comment is timely for me, as I'm looking at 510 Mathematics in Dewey in the moment, and 511.6 Combinatorics is an area that needs a bit of work done on it.

But to me sudoku are very closely connected with Dewey, because they use properties of the number 9: 9 is a perfect square, so a 9x9 square can have 9 3x3 sub-squares inside it; and 9 is 1 less than 10, so it's the number of different non-zero digits in decimal notation. This means that it's the maximum number of subtopics in Dewey Decimal notation, without resorting to devices like topics on 0 subdivisions or subtopics in a "Other" category at 9.

Melvil Dewey somewhere referred to this limit of the decimal notationas a Procrustean bed, but I can't find the quotation: the best I can find is a reference by Henry Evelyn Bliss: "For notation classifiers have constructed their various 'decimal' classifications, which in fact are inadequate procrustean classifications with decimal notations." -- which I found in http://www.sla.org/speciallibraries/ISSN00386723V20N3.PDF (using Google, of course).

The other connection between sudoku and Dewey is the number 3: every Dewey number has at least 3 digits, and there is a decimal point after the third digit. In the printed version, digits after the decimal point are grouped in bunches of 3, too.

So that suggests a Dewey sudoku puzzle: nine 9-digit Dewey numbers arranged in the sudoku arrangement, preferably each with some sensible Dewey meaning. (No, I'm not offering a prize!)

Anne Robertson

Oh Giles, how could you? It's bad enough having sudoko in the paper every day without you encouraging Dewey tragics to sink deeper in the mire of obsession.

Ye shall be Smited by the 200s any day now and classed at 234.47 for 236.21.

How To Solve Sudoku

Indeed the wikiopedia sudoku page is very very well written, though it's not really mathematicla as theres no number calculations involved. Sudoku is purely logic it would be the same if you used letters instead of numbers.

Domo Sudoku

I've never been able to solve the Rubik's cube anyway.

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