fluffguf:
When I'm totaly stuck (as with some parts of "full of ghosts" that I'm working on right now) I pick one square, and from that i start solving using X to mark filled squares until I find an error, and then I mark the first square as background. I have always considered that guessing, but i guess it is some kind of logic behind it :-)
A comment on a puzzle by cantata: "I'm always amazed at people who think that since they needed to guess, guessing is necessary. Every puzzle is solved by the computer first. Computers don't guess."
It's not guessing. You choose the proper place to start with the assumption 'What if this clue began or ended here'.
I have watched LogicPict solve puzzles. It begins with the overlaps, for which there is an easy formula to use. That's why I don't like grids that are not 5-multiples. Then it begins to fill clues, usually at edges. If that won't fit, it deletes the attempt and marks a square with a negative.
You can do this a few rows or columns in, but must be careful to look at all adjacent clues. If you have not come to a negative after it begins to get "too much to keep track of", then clear it and start someplace else.
Bruce