A variation can refer to a specific sequence of successive moves in a turn-based game, often used to specify a hypothetical future state of a game that is being played. Although the term is most commonly used in the context of
Chess
Chess is a board game for two players, called White and Black, each controlling an army of chess pieces in their color, with the objective to checkmate the opponent's king. It is sometimes called international chess or Western chess to dist ...
analysis, it has been applied to other games. It also is a useful term used when describing computer
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
-search algorithms (for example
minimax
Minimax (sometimes MinMax, MM or saddle point) is a decision rule used in artificial intelligence, decision theory, game theory, statistics, and philosophy for ''mini''mizing the possible loss for a worst case (''max''imum loss) scenario. When ...
) for playing games such as
Go[{{cite web , url=http://www.andromeda.com/people/ddyer/go/search.html, title=Searches, tree pruning and tree ordering in Go, date=21 December 2007] or
Chess
Chess is a board game for two players, called White and Black, each controlling an army of chess pieces in their color, with the objective to checkmate the opponent's king. It is sometimes called international chess or Western chess to dist ...
.
A variation can be any number of steps as long as each step would be legal if it were to be played. It is often as far ahead as a human or computer can calculate; or however long is necessary to reach a particular position of interest. It may also lead to a terminal state in the game, in which case the term "winning variation" or "losing variation" is sometimes used.
Principal variation
The principal variation refers to the particular variation that is the most advantageous to the current player, assuming each other player will respond with the move that best improves their own position. In other words, it is the "best" or "correct" line of play. In the context of
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
-searching game
artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech ...
– in which this term is most common – it may also refer to the sequence of moves that is currently ''believed'' to be the most advantageous, but is not guaranteed due to the technical limitations of the algorithm.
See also
*
Game tree
In the context of Combinatorial game theory, which typically studies sequential games with perfect information, a game tree is a graph representing all possible game states within such a game. Such games include well-known ones such as chess, ch ...
*
Backtracking
Backtracking is a class of algorithms for finding solutions to some computational problems, notably constraint satisfaction problems, that incrementally builds candidates to the solutions, and abandons a candidate ("backtracks") as soon as it d ...
*
Minimax
Minimax (sometimes MinMax, MM or saddle point) is a decision rule used in artificial intelligence, decision theory, game theory, statistics, and philosophy for ''mini''mizing the possible loss for a worst case (''max''imum loss) scenario. When ...
*
Negamax
*
Alpha-beta pruning Alphabeta is an Israeli musical group. Alphabeta or Alpha Beta may also refer to:
*The Greek alphabet, from ''Alpha'' (Αα) and ''Beta'' (Ββ), the first two letters
*Alpha Beta, a former chain of Californian supermarkets
*Alpha and beta anomers ...
*
Negascout
References
Variations
Combinatorial game theory
Game artificial intelligence
Search algorithms
Computer chess
Trees (graph theory)