ladder

A ladder (also called shicho) is a forcing sequence of diagonal ataris. The chased stone or chain must repeatedly answer each atari, while the attacker continues driving it along a zigzag path until it is captured or escapes. The sequence is used to capture an otherwise escaping stone or to determine whether a tactical continuation works before committing to it.

Unlike a simple local atari, a ladder usually travels across the board, so its result can depend on stones and liberties far from the starting position. Read the sequence all the way to its endpoint: a remote ladder breaker placed along the path, a change in liberties, or a capturing move elsewhere can invalidate the expected result.