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Published byNoel Daniel Modified over 9 years ago
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Deep Blue
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background chess: “the touchstone of the intellect” machine would model thinking, some say chess problem “sharply defined” First chess-playing machine: 1760’s Maezal Chess Automaton
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minimax algoritm generate all possible moves by player and opponent a number of steps ahead outcomes generally reside in outermost leaves of trees depth of search -> program rating
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limits initially tried to emulate humans human skills: pattern recognition and associative memory engineering approach, relies on computer’s strengths
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Tuning Mechanisms hill climbing perform a lookahead search then adjusts the parameter best fit function of machine’s evaluation of positions and the true values
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logistics 6 move lookahead: 38^12 = 9 billion billion moves each move lookahead worth about 400 rating points (world champions around 2,900)
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Deep Blue features Hsu’s single chip move generator Anantharaman’s singular extension algorithm
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Hsu’s “chess machines” evaluates 2 million positions per second 256 teamed together: 100 million positions per second 70% of chip devoted to evaluating positions
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position evaluation separate value for pieces on different squares stored endgame positions position features from grandmasters
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alpha-beta search eliminates bad moves from further consideration move ‘refuted’ if opponent can force a worst outcome than the previous estimation
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singular extensions horizon problem looks 30 or 60 moves in certain situations, checks or piece exchanges fewer choices, deeper search
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Kasparov 2.5 Deep Blue 3.5 May 3 – 11, 1997 blunder costs previously undefeated World Champion
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