In the game of Go, a ,() is a basic sequence of moves in which an attacker pursues a group in

atari Atari () is a brand name that has been owned by several entities since its inception in 1972. It is currently owned by French holding company Atari SA (formerly Infogrames) and its focus is on "video games, consumer hardware, licensing and bl ...

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 Go proverbs are traditional proverbs relating to the game of Go, generally used to help one find good moves in various situations during a game. They are generalizations and thus a particular proverb will have specific situations where it is not ...

saying "''if you don't know ladders, don't play Go.''" The ladder tactic fails 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 a play is called a ''ladder breaker''. A ladder can require reading 50 or more moves ahead, which even amateur players can do, as most of the moves are forced. Although ladders are one of the first techniques which human players learn, AlphaGo Zero was only able to handle them much later in its training than many other Go concepts. Other Go AI such as

AlphaGo AlphaGo is a computer program that plays the board game Go. It was developed by the London-based DeepMind Technologies, an acquired subsidiary of Google. Subsequent versions of AlphaGo became increasingly powerful, including a version that c ...

(before AlphaGo Zero) or KataGo use information about ladder outcomes as input

features Feature may refer to: Computing * Feature recognition, could be a hole, pocket, or notch * Feature (computer vision), could be an edge, corner or blob * Feature (machine learning), in statistics: individual measurable properties of the phenome ...

of their neural nets.

See also

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Further reading