> Just some remarks about complexity of sudoku > 1 - The difficulty of a sudoku grid is just for a human which has > to build cell by cell the missing elements **without** > enumerate (backtracking in difficult for an human :-). > 2 - A valid grid sudoku probleme has to had one and only once > solution. > 3 - The difficulty of a grid is mesured from the rules the human > has to use for filling the missing elements (without enumeration) > 4 - this grid is false because it has many solutions!
I cannot judge about the difficulty for a human, because I don't know how it could be measured. However, the book, where I encountered the puzzle, is titled "Programming Sudoku" that assumes computer solution. Besides, inappropriate formulation may make the sudoku puzzle intractable even for electronic brain; see an eloquent example on p.5 in the article "Rapid Mathematical Programming or How to Solve Sudoku Puzzles in a few Seconds" by Thorsten Koch: http://opus.kobv.de/zib/volltexte/2005/884/ps/ZR-05-51.ps . _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
