Capturing Techniques — Ladder, Net, Snapback and Connect-and-Die
The most common scene in beginner games is one player chasing the other with atari after atari. But atari alone usually doesn't capture anything, because the fleeing stones keep gaining liberties.
Why atari alone doesn't capture
Atari means a single liberty is left — but the opponent can run. Extend one point and there are two stones, with their liberties back up to three. Give atari again and they extend again, and so on.
The problem is that this chase isn't free. The chaser spends a move each time too, and those stones end up scattered without forming any proper shape. In the end the opponent escapes and lives, and you are left with a pile of useless stones.
So to capture stones, you need techniques that block the escape route in advance. The best-known are the ladder and the net.
The ladder — driving stones along in atari
A ladder chases the opponent diagonally so that the stones stay in atari every time they run. The opponent's stones are dragged all the way to the edge of the board with only one liberty and are finally captured.
The trick is to block the front of the direction they are running. When the opponent extends, block in front of that extension; when they extend again, block again. The result is a staircase running diagonally across the board.
Once a ladder works, every escape attempt only makes things worse for the opponent, since they are just adding stones to a group that will be captured anyway. The basic rule is: don't run out of a working ladder.
The ladder breaker — the one stone that ruins a ladder
A ladder has one critical weakness. If even a single opponent stone lies in its path, the ladder breaks.
When there is a stone there, the fleeing stones connect to it and gain liberties, and the chasing side is left with a mess of weak, cut-up stones. When a ladder breaks, every move you spent chasing becomes a loss, so the damage is severe.
A stone placed in that path in advance to neutralize the ladder is called a ladder breaker. If the opponent plays a ladder breaker, you have to give up on capturing with the ladder.
Always read a ladder all the way out before starting it. It runs diagonally to the far corner of the board, so check whether there is an opponent stone on that line. "I thought the ladder worked, but it didn't" is the classic accident that flips games at beginner and intermediate level. 8 Common Beginner Mistakes covers the same point.
The net — trapping stones as if in a net
The technique to use when a ladder doesn't work is the net (geta). Instead of giving atari, you play one move outside the escape space and trap the stones as if in a net.
The great advantage of a net is that ladder breakers don't matter. However far away the opponent places a stone, the trapped stones stay trapped. It is the first technique to consider whenever a ladder doesn't work.
On the other hand, a net captures a smaller area than a ladder, and the trapped stones sometimes come back to life later through ko or other tricks. Still, where a ladder fails, a net is often the reliable choice.
This is where the difference in strength between beginner and intermediate players shows most clearly: once they see the ladder doesn't work, some give up, while others think of the net.
The snapback — giving one stone to capture more
A snapback is just what the name suggests: capturing back. You let the opponent capture one of your stones, then play into the empty point left by that capture and take the whole group.
Here's how it works. When the opponent's stones are only loosely surrounded, you throw a single stone inside. If the opponent captures it, their stones end up in a shape with only one liberty. Play at that point again and you capture them all.
It looks like losing a stone, but you capture several in return, so it's a gain. It is a pattern that shows up often in life-and-death problems too, so it's well worth learning.
Connect-and-die — atari after atari
Connect-and-die (oiotoshi; chokchoksu in Korean) exploits a shape where the opponent stays in atari even after connecting. Each time they connect, their liberties don't increase, and in the end the whole group is captured.
The key is to find a position where connecting only makes things worse for the opponent. It works when the opponent's stones are already blocked from two directions and have only one way out.
Unlike the ladder and the net, connect-and-die is a little harder to spot. But it appears very often in life-and-death problems, so as you solve them it will naturally start to catch your eye.
The empty triangle — a shape that's easy to capture
So far we've covered how to capture. Now for how not to be captured.
Three stones touching at a right angle to form an L shape are called an empty triangle. It is the most famous bad shape in Go.
The reason is efficiency. You've used three stones, but they have only seven liberties. Put the same three stones in a straight line and they have eight — the bent stone folds inward and blocks one of its own liberties. It's a shape that uses more stones and is weaker for it.
Beginners usually make empty triangles because they're "nervous about being cut." But in most cases a one-point jump or a diagonal move is both sturdier and more efficient. Whenever you're about to play an empty triangle, stop for a moment and look for a different move.
There are exceptions. In life and death, an empty triangle is sometimes the only move to make an eye or to destroy the opponent's eye. The accurate rule is not "empty triangles are always bad" but "avoid them unless you have a special reason."
Capture or chase?
Finally, the most important point: chasing stones is often more profitable than capturing them.
Pour everything into capturing the opponent's stones and you'll end up playing unreasonable moves, which come back at you as counterattacks. On the other hand, if you keep up just enough pressure and firm up your surroundings while the opponent runs, the game turns in your favor without capturing anything.
Here is what chasing gains you.
- The opponent is too busy running to build territory
- You naturally gain influence or territory as you chase
- You aren't overplaying, so there's nothing to counterattack
Of course, if stones can definitely be captured, capture them. The right order is to check first whether a ladder or a net works, and if not, switch to chasing.
Summary
- Don't just chase with atari. Fleeing stones keep gaining liberties.
- Read ladders to the end. An opponent stone in the path breaks them.
- If the ladder fails, look for a net. It works regardless of ladder breakers.
- Avoid empty triangles. They use more stones and end up weaker.
- If in doubt, chase. Overplaying to capture causes the biggest losses.