A ladder (Japanese term: シチョウ shicho, Chinese 征 zheng ) is a technique for capturing stones. At each step the attacker reduces the defender's liberties from two to one.
The term ladder is also debatable. The term "stair" is much better to describe this form.
Black starts a ladder to capture the
stone.
If White tries to escape, Black can at each time play atari and White will be captured.
Clearly White should see this and not play .
Ladders may span a large part of the board. If for example Black captures the white stone in a ladder with , the ladder will go all over the board if White tries to escape, resulting in the next diagram.
If White tries to escape, the ladder will continue in this way. Of course, as it stands, this is a disaster for White.
But if there had been a white stone at a, White could now capture a stone and would stand to capture more because of all the double ataris that White can play. Such a stone which stops a ladder from working is called a ladder-breaker.
A simple technique for reading a ladder is to see six diagonal lines from the start of the shicho.[1] Unfortunately SL does not permit me to draw lines, so I have to make do with marking all the points instead. Except for a, b and c, any black stone (only) on the marked points will make a ladder-breaker.
However, if there are both black and white stones on the marked points, please read the ladder 'manually': visualise it on the board. That's not so hard, either.
Why is a black stone at a in the previous diagram (the marked stone here) not a ladder-breaker?
This diagram shows why - on the second line, White can play at instead of d in the diagram, rendering the
stone useless.
The reader might want to figure out why having a black stone at b or c in that diagram doesn't make a ladder-breaker.
Besides, note that the ladder-breaker points I have marked don't include the points on the first line. Go and figure which of these points make ladder-breakers, and which do not.
--unkx80
[1] Dieter: Kageyama says: No shortcuts. Read the ladder. Always. See Practicing Reading Out Ladders.
uxs: I agree. Being able to read them out is more useful than this "simple" technique, which apparently doesn't even work when there are just a few stones in the way. On the other hand, reading them out can be hard, especially if you try to read them as "black, white, black, white, ..." You just tend to lose track after a while.
I have found that the following works rather well: instead of reading out all stones, just read the inside stones, until you come across possible ladder breakers. In other words, if it's black chasing white stones, read the white ones. This is very easy, since it's just a simple zig-zagging across the board. Then as you come across the possible breaker stones, add (in this example) the black stones. This is also easy, as you just have to add one in the direction where you read the last white stone.
In the example, the initial situation is all the unmarked stones. When you start reading, you only read out the (marked) white stones. When you then come across the possible ladder breaker, you also read the black ones. You can stop reading when you see that puts
in atari.
(Actually, you could've already stopped reading at , since it touches the white stone below it and will therefore surely be put into atari. But it's safer to actually read it completely, and not that much more difficult.)
Klaus: In my humble opinion, all these tricks are going the wrong way. Just Read the ladder!!
"I heard from my teacher that whoever has contrivances with tricks to make them go is sure to have activities with tricks to make them go. Whoever has activities with tricks to make them go is sure to have a heart with tricks to make things go. If a heart with tricks to make things go is lodged inside your breast, the pure and simple will not be at your disposal. If the pure and simple is not at your disposal, the daemonic and vital will be unsettled. Anyone in whom the daemonic and vital is unsettled, the Way will not sustain. It isn't that I don't know, it's that I would be ashamed to make it."
(see: Graham, A.C.: Chuang-tzu: the seven inner chapters and other writings: page 186 from the book Chuang-tzu, Unwin Paperbacks, London,1986.)
uxs: If you're saying that the way I read them is a trick, I have to disagree. You ARE reading them out, but only the relevant parts.
Klaus: So the trick is leaving out the irrelevant parts? I guess it is a matter of patience to read out all moves, one by one. It might not seem to be necessary, but it is the right spirit. (Yes this is the part of eastern philosophy which western people have most problems with, and well, I might be off the mark, who knows?)
And another thing I almost forgot to add: practice! It's not too hard, and it will make you play better.
See also: