scott <sco### [at] scottcom> wrote:
> >  (A sudoku problem only makes sense if it's unambiguous, iow. it can be
> > solved unambiguously without trial-and-error, only by pure deduction.)

> Isn't trial-and-error a form of deduction?  ie "If I put a 4 in here, that 
> square will need to be 3, and then that doesn't work so it must be a 6 in 
> the original square".  Of course there are more complicated chains of logic, 
> but essentially you try one number and see if it gives a valid result.

  If trial-and-error was acceptable in a sudoku, then you could just as
well give an empty sudoku grid for someone to solve.

  The principle in sudoku puzzles is that they can be solved without having
to guess anything. The chain of required deductions may go very deep in
the hardest sudokus, but it's always possible to solve it without having
to guess.

-- 
                                                          - Warp

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