第4课：吃子 | Lesson 4: Capture

The Basic Principle of Capture

In the previous lesson, we learned about liberties. Now we come to the most exciting action in Go -- capture (also called "taking" or "removing" stones).

The principle is beautifully simple: when a stone or group of stones has all its liberties blocked (liberty count reaches zero), those stones are captured and must be removed from the board.

Think of it as a siege. You place stones around your opponent's stone, reducing its liberties one by one. When the last liberty is filled, the opposing stone becomes your prisoner and is taken off the board.

Reducing Liberties Step by Step

Let us walk through a complete capture sequence. Imagine a black stone in the center of the board with 4 liberties:

Step 1: Black has 4 liberties

Step 2: White blocks one liberty, Black has 3 left

Step 3: More liberties blocked -- only 1 left. Atari!

Now Black has only one liberty left -- the empty point to the right. This state is called "atari" -- one more move and the stone will be captured.

Capturing a Single Stone

Capturing a lone stone is the simplest case. Let us look at examples in different positions:

Capturing a Corner Stone

A corner stone has only 2 liberties, so it takes just 2 moves to capture:

The black stone in the top-left corner is completely surrounded by white stones. Its liberty count is zero, and it will be removed from the board!

Capturing an Edge Stone

An edge stone has 3 liberties and requires 3 moves to surround:

This black stone on the left edge has all three liberties blocked by white stones and will be captured.

Capturing a Group of Stones

It is not just single stones that can be captured -- an entire connected group can be captured all at once. As long as every liberty of the group is blocked, all stones in the group are removed simultaneously.

Here is an example of capturing two connected black stones:

These two connected black stones are completely surrounded by white, with zero liberties remaining. Both will be removed from the board at the same time. Capturing a group yields a bigger reward than capturing a single stone!

What to Do When You Are in Atari

When your stone is in atari (only one liberty left), do not panic! You typically have several options:

• Run (extend): Connect your stone toward open space to gain more liberties. This is the most common response.
• Counter-capture: If the opponent's surrounding stones are also low on liberties, you might be able to capture them instead.
• Sacrifice: Sometimes, giving up a small, unimportant stone and using your move elsewhere for a bigger gain is the smarter play. Do not throw good stones after bad ones.

Capture and Scoring

In Cute Go, scoring is simplified: the player with more stones on the board wins. This means every stone you capture gives you a direct advantage -- the captured stone disappears from the board, reducing your opponent's count.

In formal Go rules, capture is equally important. Captured stones (called "prisoners") are saved and used at the end of the game to reduce the opponent's territory. Under any ruleset, capture is one of the most direct ways to gain an advantage.

With capture under your belt, you are ready to start playing Go! In the coming lessons, we will explore more concepts including connection, the suicide rule, and ko.