锯齿形追逐 — 横跨整个棋盘的吃子手段
征子（日语：シチョウ，Shicho）是围棋中最经典、最美丽的战术之一。当一颗或一组棋子被叫吃后，每次逃跑都会被再次叫吃，形成一条锯齿形的追逐路线，最终棋子被追到棋盘边缘而被吃掉——这就是征子。
征子的路径如同楼梯一般呈对角线方向延伸，英文因此称为"Ladder"（梯子）。征子是初中级棋手必须掌握的重要技术，因为它涉及到对整个棋盘的全局判断。一个征子能否成功，不仅取决于局部的形状，更取决于征子路线上是否有对方的棋子（征子有利或不利）。
征子之所以成立，是因为被追的棋子每次逃跑后始终只有2口气。追的一方每次都能堵住其中1口气，使被追方再次处于叫吃状态。这个过程不断重复，形成一条对角线路径。
征子成功的条件：
如果征子路线上有对方的棋子，被追方逃到那里时就会多出额外的气，使得追逐失败。这就是所谓的"引征"——对方预先布置棋子来破坏你的征子。
让我们看一个征子如何开始的例子：
征子的起点：黑棋叫吃白子，白棋只剩下方一口气
白棋被黑棋从上方和左方包围，只剩下方一口气。如果白棋向下逃跑，黑棋继续从右侧叫吃；白棋再向右逃跑，黑棋又从下方叫吃……如此反复，形成征子。
征子的追逐过程就像楼梯一样：
征子追逐过程：白棋每次逃跑都被黑棋再次叫吃
可以看到，白棋的逃跑路线形成了一条阶梯形的对角线。每一步逃跑后，白棋都只有2口气，黑棋都能堵住1口气继续叫吃。白棋永远无法获得第3口气，最终会被追到棋盘边缘而被吃掉。
判断征子是否成功，需要检查征子路线上（对角线方向）是否有对方的棋子：
如果征子路线上没有对方的棋子，征子一直追到棋盘边缘，被追方最终被吃。这种情况叫"征子有利"。
如果征子路线上有对方的棋子，被追方逃到那颗棋子旁边时会多出额外的气，超过2口气后就无法继续叫吃，征子失败。这种情况叫"征子不利"。
征子不利：路线上有白棋的援兵，征子会失败
引征是一种高级战术，指的是提前在征子路线上布置一颗棋子，使征子变得不利。引征的棋子本身可能看起来很孤立、没有什么作用，但如果它能破坏对方的征子，那就有了巨大的战略价值。
引征的时机非常微妙：
判断引征的有效性也需要计算整条征子路线——引征子必须恰好在路线上才能发挥作用。
掌握征子后，可以运用以下技巧提升实战水平：
每当你打算发起征子时，先花几秒钟用眼睛沿着对角线方向检查整条路线。有没有对方的棋子？如果有，征子可能不利。
即使你不打算真正发起征子，威胁征子也能迫使对方做出某些应对，从而让你在其他地方获得先手。
有时候，故意让一颗棋子被征子追逐，然后利用征子路线上形成的影响力来获得其他方面的利益。这是一种高级的弃子战术。
如果征子因为引征而失败，可以考虑使用"枷"（网）来替代。枷不受引征影响，是征子的重要替代手段。
The ladder (Japanese: Shicho) is one of the most classic and elegant tactics in Go. When a stone or group is put in atari and every escape attempt results in being put in atari again, a zigzag chase pattern forms across the board, eventually driving the stones to the edge where they are captured — this is the ladder.
The path of a ladder extends diagonally like a staircase, which is why it is called a "ladder" in English. The ladder is an essential technique that beginning and intermediate players must master, because it involves whole-board judgment. Whether a ladder succeeds depends not only on the local shape, but also on whether the opponent has stones along the ladder path (ladder breakers).
The ladder works because the fleeing stones always have exactly 2 liberties after each escape move. The pursuing player can always block one of those liberties, putting the fleeing stones back into atari. This process repeats, forming a diagonal path across the board.
Conditions for a successful ladder:
If the opponent has a stone along the ladder path, the fleeing stones will gain extra liberties when they reach that stone, causing the chase to fail. This stone is called a "ladder breaker" — a stone the opponent has strategically placed to defeat the ladder.
Let's look at how a ladder begins:
Ladder starting point: Black puts White in atari with only one liberty below
The white stone is surrounded from above and the left by black stones, with only one liberty remaining below. If White escapes downward, Black continues the atari from the right; if White then escapes to the right, Black ataris from below — and so on, forming the ladder.
The chase in a ladder looks like a staircase:
Ladder sequence: White is continuously put in atari by Black in a zigzag pattern
As you can see, White's escape path forms a staircase-like diagonal line. After every escape, White has only 2 liberties, and Black can always block one to continue the atari. White can never gain a third liberty and will eventually be chased to the board edge and captured.
To determine whether a ladder will succeed, you need to check the entire diagonal path for opponent stones:
If there are no opponent stones along the ladder path, the chase continues all the way to the board edge, and the fleeing stones are captured. This is called a "favorable ladder."
If there is an opponent stone along the ladder path, the fleeing stones will gain extra liberties when they reach that stone. With more than 2 liberties, the atari chain breaks and the ladder fails. This is called an "unfavorable ladder."
Unfavorable ladder: A White reinforcement along the path will break the ladder
A ladder breaker is an advanced tactic where a player places a stone in advance along the ladder path to make the ladder fail. The ladder breaker stone itself may look isolated and useless, but if it can defeat the opponent's ladder, it carries enormous strategic value.
The timing of a ladder breaker is very delicate:
Evaluating the effectiveness of a ladder breaker also requires reading the entire ladder path — the breaker must be precisely positioned along the path to work.
After mastering the ladder concept, apply these techniques to improve your game:
Whenever you plan to initiate a ladder, spend a few seconds visually tracing the diagonal path. Are there any opponent stones along the way? If so, the ladder may fail.
Even if you don't intend to actually start a ladder, the threat of a ladder can force your opponent to make certain responses, allowing you to gain initiative elsewhere on the board.
Sometimes, deliberately allowing your stones to be chased in a ladder can be used as a sacrifice tactic. The influence created along the ladder path can yield benefits in other areas. This is an advanced sacrifice technique.
If a ladder fails due to a ladder breaker, consider using a "net" (geta) instead. Nets are not affected by ladder breakers and serve as an important alternative to ladders.