Horizon Effect
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Horizon Effect
The horizon effect, also known as the horizon problem, is a problem in artificial intelligence whereby, in many games, the number of possible states or positions is immense and computers can only feasibly search a small portion of them, typically a few plies down the game tree. Thus, for a computer searching only a fixed number of plies, there is a possibility that it will make a poor long-term move. The drawbacks of the move are not "visible" because the computer does not search to the depth at which its evaluation function reveals the true evaluation of the line. The analogy is to peering at a distance on a sphere like the earth, but a threat being beneath the horizon and hence unseen. When evaluating a large game tree using techniques such as minimax with alpha-beta pruning, search depth is limited for feasibility reasons. However, evaluating a partial tree may give a misleading result. When a significant change exists just over the horizon of the search depth, the computat ...
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Artificial Intelligence
Artificial intelligence (AI) is the capability of computer, computational systems to perform tasks typically associated with human intelligence, such as learning, reasoning, problem-solving, perception, and decision-making. It is a field of research in computer science that develops and studies methods and software that enable machines to machine perception, perceive their environment and use machine learning, learning and intelligence to take actions that maximize their chances of achieving defined goals. High-profile applications of AI include advanced web search engines (e.g., Google Search); recommendation systems (used by YouTube, Amazon (company), Amazon, and Netflix); virtual assistants (e.g., Google Assistant, Siri, and Amazon Alexa, Alexa); autonomous vehicles (e.g., Waymo); Generative artificial intelligence, generative and Computational creativity, creative tools (e.g., ChatGPT and AI art); and Superintelligence, superhuman play and analysis in strategy games (e.g., ...
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Chess
Chess is a board game for two players. It is an abstract strategy game that involves Perfect information, no hidden information and no elements of game of chance, chance. It is played on a square chessboard, board consisting of 64 squares arranged in an 8×8 grid. The players, referred to as White and Black in chess, "White" and "Black", each control sixteen Chess piece, pieces: one king (chess), king, one queen (chess), queen, two rook (chess), rooks, two bishop (chess), bishops, two knight (chess), knights, and eight pawn (chess), pawns, with each type of piece having a different pattern of movement. An enemy piece may be captured (removed from the board) by moving one's own piece onto the square it occupies. The object of the game is to "checkmate" (threaten with inescapable capture) the enemy king. There are also several ways a game can end in a draw (chess), draw. The recorded history of chess goes back to at least the emergence of chaturanga—also thought to be an ancesto ...
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Monte Carlo Tree Search
In computer science, Monte Carlo tree search (MCTS) is a heuristic search algorithm for some kinds of decision processes, most notably those employed in software that plays board games. In that context MCTS is used to solve the game tree. MCTS was combined with neural networks in 2016 and has been used in multiple board games like Chess, Shogi, Checkers, Backgammon, Contract Bridge, Go, Scrabble, and Clobber as well as in turn-based-strategy video games (such as Total War: Rome II's implementation in the high level campaign AI) and applications outside of games. History Monte Carlo method The Monte Carlo method, which uses random sampling for deterministic problems which are difficult or impossible to solve using other approaches, dates back to the 1940s. In his 1987 PhD thesis, Bruce Abramson combined minimax search with an ''expected-outcome model'' based on random game playouts to the end, instead of the usual static evaluation function. Abramson said the expected-out ...
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Anti-computer Tactics
Anti-computer tactics are methods used by humans to try to beat computer opponents at various games, most typically board games such as chess and Arimaa. They are most associated with competitions against computer AIs that are playing to their utmost to win, rather than AIs merely programmed to be an interesting challenge that can be given intentional weaknesses and quirks by the programmer (as in many video game AIs). Such tactics are most associated with the era when AIs searched a game tree with an evaluation function looking for promising moves, often with Alpha–beta pruning or other minimax algorithms used to narrow the search. Against such algorithms, a common tactic is to play conservatively aiming for a long-term advantage. The theory is that this advantage will manifest slowly enough that the computer is unable to notice in its search, and the computer won't play around the threat correctly. This may result in, for example, a subtle advantage that eventually turns i ...
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Fog Of War
The fog of war is the uncertainty in situational awareness experienced by participants in military operations. The term seeks to capture the uncertainty regarding one's own capability, adversary capability, and adversary Intent (Military), intent during an engagement, operation, or campaign. Military forces try to reduce the fog of war through military intelligence and friendly force tracking systems. The term has become commonly used to define uncertainty mechanics in war gaming, wargames. Origin The word "fog" (), but not the exact phrase, in reference to 'uncertainty in war' was introduced by the Prussian military analyst Carl von Clausewitz in his posthumously published book, ''Vom Kriege'' (1832), the English translation of which was published as ''On War'' (1873): It has been pointed out that von Clausewitz does not use the exact phrase "fog of war", and also uses multiple similar metaphors, such as "twilight" and "moonlight", to describe a 'lack of clarity'. The fi ...
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Atari (go)
Players of the game of Go often use jargon to describe situations on the board and surrounding the game. Such technical terms are likely to be encountered in books and articles about Go in English as well as other languages. Many of these terms have been borrowed from Japanese, mostly when no short equivalent English term could be found. This article gives an overview of the most important terms. Use of Japanese terms Although Go originated in China, the current English and Western technical vocabulary borrows a high proportion of terms from the Japanese language because it was through Japan that the West was introduced to Go. Many of these terms are from a jargon used for technical Go writing and are to some extent specially developed for Go journalism. Some authors of English-language Go materials avoid use of Japanese technical terms, and the way they are applied can differ in subtle ways from the original meanings. A few Korean-language terms have come into use (e.g., ...
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Ladder (Go)
In the game of Go, a ,() is a basic sequence of moves in which an attacker pursues a group in atari 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 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 it ...
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Computer Go
Computer Go is the field of artificial intelligence (AI) dedicated to creating a computer program that plays the traditional board game Go. The field is sharply divided into two eras. Before 2015, the programs of the era were weak. The best efforts of the 1980s and 1990s produced only AIs that could be defeated by beginners, and AIs of the early 2000s were intermediate level at best. Professionals could defeat these programs even given handicaps of 10+ stones in favor of the AI. Many of the algorithms such as alpha-beta minimax that performed well as AIs for checkers and chess fell apart on Go's 19x19 board, as there were too many branching possibilities to consider. Creation of a human professional quality program with the techniques and hardware of the time was out of reach. Some AI researchers speculated that the problem was unsolvable without creation of human-like AI. The application of Monte Carlo tree search to Go algorithms provided a notable improvement in the ...
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Go (board Game)
# Go is an abstract strategy game, abstract strategy board game for two players in which the aim is to fence off 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 game continuously played to the present day. A 2016 survey by the International Go Federation's 75 member nations found that there are over 46 million people worldwide who know how to play Go, and over 20 million current players, the majority of whom live in East Asia. The Game piece (board game), playing pieces are called ''Go equipment#Stones, stones''. One player uses the white stones and the other black stones. The players take turns placing their stones on the vacant intersections (''points'') on the #Boards, board. Once placed, stones may not be moved, but ''captured stones'' are immediately removed from the board. A single stone (or connected group of stones) is ''captured'' when surrounded by the opponent's stones on all Orthogona ...
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Perpetual Check
In the game of chess, perpetual check is a situation in which one player can play an unending series of checks from which the defending player cannot escape. This typically arises when the player who is checking feels their position in the game is inferior, they cannot deliver checkmate, and wish to a draw. A draw by perpetual check is no longer one of the rules of chess, but will eventually allow a draw claim by either threefold repetition or the fifty-move rule. Players usually agree to a draw long before that. Perpetual check can also occur in other forms of chess, although the rules relating to it might differ. For example, giving perpetual check is not allowed in shogi and xiangqi, where doing so leads to an automatic loss for the giver. Examples In this diagram, Black is ahead a rook, a bishop, and a pawn, which would normally be a decisive advantage. But White, to move, can draw by perpetual check: : 1. Qe8+ Kh7 : 2. Qh5+ Kg8 : 3. Qe8+ etc. The same position w ...
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Sacrifice (chess)
In chess, a sacrifice is a move that gives up a piece with the objective of gaining tactical or positional compensation in other forms. A sacrifice could also be a deliberate exchange of a chess piece of higher value for an opponent's piece of lower value. Any chess piece except the king may be sacrificed. Because players usually try to hold on to their own pieces, offering a sacrifice can come as an unpleasant surprise to one's opponent, putting them off balance and causing them to waste precious time trying to calculate whether the sacrifice is sound or not, and whether to accept it. Sacrificing one's queen (the most valuable piece), or a string of pieces, adds to the surprise, and such games can be awarded . Types of sacrifice Real versus sham Rudolf Spielmann proposed a division between sham and real sacrifices: * In a ''real sacrifice'', the sacrificing player will often have to play on with less than their opponent for quite some time. * In a ''sham sacrifice'', ...
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Leaf Node
In computer science, a tree is a widely used abstract data type that represents a hierarchical tree structure with a set of connected nodes. Each node in the tree can be connected to many children (depending on the type of tree), but must be connected to exactly one parent, except for the ''root'' node, which has no parent (i.e., the root node as the top-most node in the tree hierarchy). These constraints mean there are no cycles or "loops" (no node can be its own ancestor), and also that each child can be treated like the root node of its own subtree, making recursion a useful technique for tree traversal. In contrast to linear data structures, many trees cannot be represented by relationships between neighboring nodes (parent and children nodes of a node under consideration, if they exist) in a single straight line (called edge or link between two adjacent nodes). Binary trees are a commonly used type, which constrain the number of children for each parent to at most two. When ...
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