Sudoku

'Guessing'

Idéa

Adviser

Safe digits

Warning technical discussion...

Sometimes your sudoku ends up in a rather locked situation where it seems impossible to find any more safe digits. This is often the case with the more difficult ones. Should you end up in such a situation you will have to make a guess. If you did the right guess you will end up with a solved sudoku, if your assumption was in error you will sooner or later end up in a situation where you could not put in new digits without producing duplicates. The Adviser gives you some help in these situations.

You could select two types of warnings when you make a mistake, ‘Duplicate’ or ‘Solution’. In any case if you make a mistake the background in the cell will be red, which happens directly when you leave a cell with the indicated error. If you ask the Adviser to check against the solution will directly know if your guess is correct, but if you think that is too much cheating you could use another method. Just save the sudoku with the ‘Save’-button and if you end up in a dead-end, just reload with the ‘Open’-button and you are back where you where before the guess. Equivalent to using thin writing and a rubber manually.

When you eneter a new sudoku into the Adviser, Nizze tries to solve the problem to have a correct solution handy if you need assistance. If Nizze needs to guess more than once he will fail, which doesn’t happen too often, but if you try him on diabolic ones it might happen. Please let us know so we could send him into a training camp…

When solving sudokus manually and the safe digits ends to appear, it is common to calculate candidates for the empties, they are often referred to as ’pencil-marks’. To do this manually is rather cumbersome and error prone, and the Advisor could help you in doing it. Are you just looking for certain digits this could also be done, else it is easy to drawn in all the information displayed. At the moment it is not possible to enter your own pencil-marks into the sudoku, some features are saved for the next release. You have to trust Nizze’s…

No yellows as far as the eye could reach (when 18 of 55 is done). This is the signal from the Advisor that no more of the four types of safe digits is to be found. In the picture you could se what happens if you put on help level ‘All’, the sudoku is crowded with numbers all over. In the turquoise fields are the missing digits in the rows, columns and boxes. The small digits in the empties are the candidates displayed.

If you work with this problem for a while you could reduce some of the candidates that Nizze doesn’t understand at the moment. Looking at row 7 you see that some more conclusions could be drawn. Since 1 and 7 are the only possible values in the cells to the right, these digits could be removed as candidates in the other cells of this row. There might be more of those found given you one or two more digits after half an hour of analysis. But finally you will probably have to guess..

Down at the right hand side is some button in the Adviser.

In this dialogue you could define all the settings for the help Nizze gives to you. You could set the type of warnings shown when you do mistakes. ‘Duplicate’, means you will be warned when doing ‘silly’ mistakes, i.e. the entry you have done is a duplicate. ‘Solution’ means that the Adviser check against the correct solution he has found and shows a deviation from this immediately.

With all hints activated the display of the sudoku could look like this. We see that only 5 is possible in the first cell on the second row. A red corner in the upper right corner indicates that the cell contains a hint that will be shown if you hover the mouse over it, it will show the reason and the digit if you have asked for it.

Putting the 5 in the right place automatically updates the pencil-marks.