Draw a line for each missing digit? Does it mean i have to draw a line for each raw and column that doesn't have a specific digit yet? If so, then lines need to cross at every cell with a candidate for the digit, so this technique is just drawing lines without any reason Anyways, i can see in the example that Ruud (i think it was him who wrote the guide) DIDN'T draw a line for EVERY raw and column that has cells with candidate 9. So i think that number of lines to be equal to the number of missing 9s, am I right? If so, there's only one 9 place on the grid and 8 remaining, and there are exactly 9 lines drawn. So i think I know the secret. Now, if I'm right, (but i'm not sure) then how do i know where to draw them? Or does is have to be at least 1 way to place the lines that they don't cross each other at the cells with candidates? If so, won't it require a lot of trying to place them and isn't it then even easier to scan the grid and look for X-Wings, Swordfishes and other raw/column subset techniques? Or maybe it's not too hard to find a way to draw the lines?If you are able to draw a line for each missing digit either horizontally or vertically in such a way that no two lines cross any of the remaining candidates, you are allowed to remove all digits not covered by a line.
What i really would need is practice, yet, I don't really have puzzles which i could use to practice, so I'm soooo confused that I don't wanna even read the solving guide further until i master fishing.
So, any information, tips, explanation?