An Alternative Approach for Playing Complex Games like Chess. 1Alternative Game Playing Approach Jan...
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Transcript of An Alternative Approach for Playing Complex Games like Chess. 1Alternative Game Playing Approach Jan...
An Alternative Approach for Playing Complex Games like Chess.
1Alternative Game Playing Approach
Jan LemeireMay 19th 2008
Pag.Jan Lemeire / 142Alternative Game Playing Approach
Research TopicsComputer versus Brain
Deep Blue: 600 million evaluations/second
Chess experts: 10 patterns/second
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Brute force chess playing
Most succesful!
Evaluation of future states
Alternative Game Playing Approach3
White plays
Black plays
White plays
Black plays
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Alternative game playing approaches
Decision-making: used to map states to operators.Explanation-Based Learning (EBL): try to learn the states that lead to advantageous situations.States are identified by patterns.
4Alternative Game Playing Approach
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Game State Evaluation
5Alternative Game Playing Approach
All approaches rely on a game state evaluation:– measure ‘goodness’ of stateOr– to select a good move.
My hypothesis is based on a problem with state evaluation.
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Example: fork pattern.
Opportunity!Fork pattern is way to
success!
Counter move…Fork pattern does
not give an advantage…
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Correct evaluation problem
Consider two relevant patterns, P1 and P2 evaluation = f(P1, P2) 4 regions in state space should be considered:
7Alternative Game Playing Approach
P1 & P2
P1 & P2
P1 & P2
P1 & P2
W: advantageous for whiteB: advantageous for black0: no advantageFor example ‘fork’ and ‘make chess’
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Correct evaluation problem
Evaluation = f(features or patterns).
One has to capture all situations in which the pattern leads to a successful outcome, all counter plans have to be excluded.Evaluation of pattern combinations heavily depends on game context!Features alone do not give us the right information.
8Alternative Game Playing Approach
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Known problem in literature
Deep Blue relied on looking as far as possible into the future and just a simple state evaluation.
“However, even simple patterns like a knight fork are non-trivial to formalize…” Fürnkranz 2001.
“Learning too many too specialized rules with explanation-based learning”, Minton 1984, Epstein, Gelfand and Joanna Lesniak 1996 (HOYLE pattern-based learning).
“Even in simple games, such as tic-tac-toe, 45 concepts were learned with 52 exception clauses”, Fawcett and Utgoff 1991.
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Hypothesis
“The impact of a pattern on the outcome of the game entirely depends on whether or not some states, called the effects, are attained during the continuation of the game.”
10Alternative Game Playing Approach
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New kind of knowledge
Fork win a pieceWeak king’s defense successful attack on the king Pressure successful combination
Alternative Game Playing Approach11
Patterns denote opportunities, advantages have to be verified.
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Alternative game playing
12Alternative Game Playing Approach
White recognizes pattern 1:
White has to check in game tree whether - a positive effect can be attained: - black can neutralize pattern 1:
1
1
1
Hypothesis:More efficient than brute
force tree exploration
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Similar to human game playing!
Chess experts rely on falsification (Cowley and Byrne, 2004).Humans can easily recognize and identify patterns, but have difficulties formally defining them.Humans can pinpoint the patterns that were decisive in a game, can answer why-questions.
not by current computer game playingHumans can reason about a game.
13Alternative Game Playing Approach
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Hypothesis requires theoretical or experimental confirmation…
14Alternative Game Playing Approach
Test by simulation of games no decisive conclusion yet.
Pattern engine needed that is able to:Describe patternsRecognize patternsExtract patternsReason with patterns
“White attacks two black pieces with a fork, one of the pieces can make chess. White thus has to move its king and black can bring his second piece into safety.”
Theoretical proof?