In the

game of Go Go is an abstract strategy game, abstract strategy board game for two players in which the aim is to surround more territory than the opponent. The game was invented in China more than 2,500 years ago and is believed to be the oldest board gam ...

, 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 publisher Atari SA through a subsidiary named Atari Interactive. The original Atari, Inc. (1972–1992), Atari, Inc., ...

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, GO, G.O., or Go! may refer to: Arts and entertainment Games and sport * Go (game), a board game for two players * '' Travel Go'' (formerly ''Go – The International Travel Game''), a game based on world travel * Go, the starting position l ...

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 AlphaGo Zero is a version of DeepMind's Go software AlphaGo. AlphaGo's team published an article in the journal ''Nature'' on 19 October 2017, introducing AlphaGo Zero, a version created without using data from human games, and stronger than any ...

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 (game), Go. It was developed by DeepMind Technologies a subsidiary of Google (now Alphabet Inc.). Subsequent versions of AlphaGo became increasingly powerful, including a version that ...

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

features Feature may refer to: Computing * Feature (CAD), could be a hole, pocket, or notch * Feature (computer vision), could be an edge, corner or blob * Feature (software design) is an intentional distinguishing characteristic of a software item ...

of their

neural nets Artificial neural networks (ANNs), usually simply called neural networks (NNs) or neural nets, are computing systems inspired by the biological neural networks that constitute animal brains. An ANN is based on a collection of connected units ...

See also

References

Further reading