by **Animator** » Tue May 17, 2005 6:24 pm

For the record: the only time you might need an X-wing is on the very hard puzzle. You would need a swordfish when you go on beyond very hard... but the program does not generate those puzzles... (unfortunally I may add)

Here is a really basic explenation of an X-Wing (the same goes for rows too):

* First, look for a column in which a certain number has only two possible candidate-cells.

* Second, look for another column which has two possible candidate-cells for the same number aswell.

* You have an X-wing if, and only if: the first candidate of column A is on the same row as the first candidate of column B and the second candidate of column A is on the same row as the second candidate of column B

* When you found this you can remove the number as candidate from all other cells on the two rows (except in column A and column B).

Ofcourse explaining it only with words is hard, so feel free to look at the other posts asking help with a 'Very Hard' puzzle, or the ones that explains X-wings