Broken ladder

In the game of Go, a Ladder (シチョウ, Shichou) is a basic sequence of moves in which an attacker pursues a group in atari in a zig-zag pattern across the board. If there are no intervening stones, the group will hit the edge of the board and be captured.

The sequence is so basic that there is a Go proverb saying "if you don't know ladders, don't play Go."

The ladder tactic is often a failure, if there are stones supporting those being chased close enough to the diagonal path of the ladder. Such a failing ladder is called a broken ladder. Secondary double threat tactics around ladders, involving playing a stone in such a way as to break the ladder and also create some other possibility, are potentially very complex. Such plays are called ladder-breakers.

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Wikipedia