(Super Sudoku Book, iPad, v2.1) In the expert and insane puzzles, the hint sometimes shows "Locked Single", without any square suggestion. Any explanation of this term? There's no definition of it in the iPad user guide page, and it doesn't correspond to other definitions of "locked single" I've found on the Internet. Thanks, RichK

You my friend just found a bug! Just in time to be fixed in the 2.2 version of the game as well. So thanks for catching that!

It's a mistake in the graphics and I'm not sure how we missed it. It should be saying "No Hint Found" or "No Hint Available".

I suppose in some ways my answer is worse than if it had really been finding a locked single and we had just forgot to explain what a locked single is. The problem is that the only kinds of hints that are easily explainable by highlighting a cell are naked and hidden singles. All other solving techniques are candidate reducing methods, which don't directly point to an answer for a cell. What those other methods do is reduce what is possible for a cell, and then after removing that candidate it will either reveal a hidden or naked single, or help in the removing of another candidate somewhere else.. and so on.

So the unfortunate news here is that sometimes, only on the harder puzzles, it will say No Hint Available. Then you have to employ candidate reducing methods yourself.

Locked Single was actually a typo anyway. The real name of the method is locked candidates, and in the beta versions of sudoku book it could find locked candidates. But again, because there was no simple way to communicate this via a hint I removed it. (but the code is still there - and that trace was left behind).

Check out the solving sudoku part of the user guide:

http://www.badweaselgames.com/sb/iPadHelp.html#solving

Locked candidates are the same thing as pointing pairs. Different people call it different things I guess. But it is when you have a candidate that inside of a block only exist in a row or a column.. these are locked to that row or column inside that block - and therefore are unlocked or should be removed from the rest of the row or column.

Sorry about the confusion. It's already fixed in our v2.2 which is awaiting the release of iOS 4.2.