There’s no math involved in solving a Sudoko, unless I’ve been doing it wrong all these years.]]>

I enoy cryptic crosswords and Sudoko but I have to ask, is this the best use that could be made of a supercomputer – 12 months to check the least clues that can be used in Sudoko??? Seriously???????

]]>Sorry, but with all respect that’s wrong. Group and number theory DO NOT underpin sudoku. Solving a sudoku puzzle is no more than a process of physical elimination – ultimately, deciding that a digit must go in a certain location because it is physically blocked from going anywhere else. If I want to put a can of beans in a cupboard and all but one shelf is completely full I’ll put it on the shelf that isn’t; there is no mathematical process at work and the logic behind sudoku is identical. Numbers are used because they are the most convenient – it could be letters, drawings of fruit, coloured buttons.

The main inaccuracy in the article, though, is that it equates the toughness of a puzzle with the number of seed numbers in the grid. A 17-seed puzzle may actually be very easy, and a 36-seed puzzle extremely difficult. What matters is the type of logical step required to either place a digit or eliminate a candidate.

I’ve found it’s reasonably easy to create a sudoku of 18 seeds. You use the left and right central regions and place 3 consecutive digits in each, one in the upper row and one in the lower row. Staying symmetrical, in the top and bottom rows of regions you place 3 consecutive digits in the middle region and 3 more (on different rows) left/right. I’ve produced several of these and some were calculated to be ‘very easy’ – that is, every required move is based on a cell having only one potential candidate.

On the other hand you can have a puzzle where only a dozen or so cells are unfilled, but the next move needs you to find X/Y-Wing, Skyscraper, Turbot Fish, Squirmbag or any other of the ‘colours’ shapes.]]>

Sudoku can be solved using Maths bt logic is easier!

Also here we call it Maths, bt in the US it’s math.

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