Example of Splits
This is a screenshot
Splits:
If all the other Analyses have failed to find a complete Solution, then the Splits Analysis may be deployed. Whether you
consider this approach 'logical trial-and-error', or just 'guessing', the procedure is the same: For each Square which contains a Pair (coloured pink), each Possible of the Pair is trialed in turn to see if it leads to a Contradiction - in which case the other Possible of the Pair must be the true Solution. If no Contradiction is forthcoming, the Analysis trials (or 'guesses') the next Pair and so on until a complete Solution is obtained.
In this first example, all the other Analyses have brought the SuDoku to this point, but can progress no further. The Splits Analysis indicates the only two possible Solutions for each Square containing a Pair. Clicking the STEP button one more time will resolve the Pairs and bring up a complete Solution.
Unlike all the other Analyses, a Solution obtained with Splits is not guaranteed to be unique - indeed, the fact that it has needed to be deployed at all is usually an indication that the SuDoku is not a true puzzle with only one Solution.
Second Example of Splits
This is a screenshot
In this second example, an additional Start Position Square has been added which allows the other Analyses to progress much further, but
the last few Squares still cannot be solved and the Splits Analysis kicks in. This indicates the SuDoku does not have a unique Solution -
the 5s and 8s are interchangeable between the two possible complete Solutions.