Depends on what you mean by a proof. If the sudoku verb in the J Wiki essay fails to find a solution that means that there isn't one.
If you want a proof that is more convincing to a human then study the phrases following "The following phrases show the intermediate steps leading to a solution". The algorithm basically is to find all the forced moves, resulting in F. Then pick a square of F with the fewest number of possible moves, try each possible move, and if none of them lead to a solution, then the initial grid does not have a solution. On Thu, May 30, 2013 at 10:20 AM, Raul Miller <[email protected]> wrote: > http://www.jsoftware.com/jwiki/Essays/Sudoku > http://puzzles.usatoday.com/sudoku#/2013/05/22 > > (caution: that usatoday page often has a 30 second preroll ad, > hopefully that will be toned down before too long.) > > $u20130522 > 81 > 10#.3 3 3 3$u20130522 > 900 30 2 > 3 26 0 > 2 190 430 > > 350 60 90 > 2 40 700 > 70 50 26 > > 49 75 80 > 0 610 500 > 100 80 3 > sudoku u20130522 > |index error: free > > Is this really a sudoku puzzle without a solution? > > If so, what's a simple way of proving this? > > Thanks, > > -- > Raul > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
