In chess, ply refers to a half-move: one turn of one of the players. Thus, after 20 moves of a chess game, 40 ply have been completed, 20 by white and 20 by black. In the game of go, by contrast, a ply is the normal unit of counting moves; so for example to say that a game is 250 moves long is to imply 250 ply. It is thought that good human chess players can often look 10 or more ply ahead. Listen to this article · (info) This audio file was created from the revision dated 2005-09-05, and does not reflect subsequent edits to the article. ... Go is a strategic, two-player board game originating in ancient China between 2000 BC and 200 BC. Go is a popular game in East Asia. ...

In computer chess the concept of ply becomes important because one ply corresponds to one level of the game tree. It has been found that an increase in search depth of one ply corresponds on the average to an increase in playing strength of approximately 80 Elo points. The Deep Blue chess computer which defeated Kasparov in 1997 could search to a depth of 12 ply. 1990s Pressure-sensory Chess Computer with LCD screen The idea of creating a chess-playing machine dates back to the eighteenth century. ... In game theory, a game tree is a directed graph whose nodes are positions in a game and whose edges are moves. ... The ELO rating system is a method for calculating the relative skill levels of players in two-player games such as chess and Go. ... Kasparov vs. ... This article contains information that has not been verified and thus might not be reliable. ...

Arthur Samuel originated the term in his paper on machine learning in 1959 [1]. Consider the word 'reply'—the response, or comeback, to an utterance: it might be thought of as the re-ply to an initial ply.

See also: minimax algorithm. Minimax is a method in decision theory for minimizing the expected maximum loss. ...