Mastering Chess An overview of common chess AI
- Slides: 18
Mastering Chess An overview of common chess AI Adam Veres
Everybody knows chess, right?
ELO Rating System Important context on how players are rated • Arpad Elo • Hungarian-born, American physics professor – creator.
ELO Rating System, cont. • Numerical system for calculating relative skill level of players • Higher number = better player • Players avoid situations that damage their ELO. • Picking events • Not just chess
USCF Rating Tiers Senior Master 2400+ Master 2200+ (This encompasses the 93 -98 th percentile of all rated players in America) Expert 2000+ ‘A’ Player 1800+ ‘B’ Player 1600+ ‘C’ Player 1400+ ‘D’ Player 1200+ ‘E’ Player 1000+ ‘F’ Player 800+ ‘G’ Player 600+ ‘H’ Player 400+ ‘I’ Player -400
Computer chess! Some history on computers playing chess • ~1770 • The Turk • Fake automaton • Wolfgang von Kempelen § Hungarian inventor
Alan Turing • 1951 developed, on paper, a program capable of playing a full game of chess • Work backwards from ‘win’ conditions and accept moves that work towards that goal • Turing assumed infinite processing power and storage space • Ratio W/B
Chessmaster • 1986 - The Chessmaster 2000 • The manufacturer rated the game at 2000 Elo USCF, in reality it plays at approximately 1750 -1800 USCF. • This is “B” rated in 1986! • Best selling Chess series of all time.
Deep Blue 1997 IBM’s Deep Blue defeats Gary Kasparov after a six game match. Deep Blue relied on hardware for to evaluate over 200 million moves per second
Beyond Deep Blue • Deep Fritz version 10 ran on a machine running two Intel Core 2 Duo processors. • 8 million moves per second • Average depth search of 17 -18 using heuristics to evaluate choices • About 6 billion possible positions observed before actually making a move • Vladimir Krammik loses 2 -4 to Deep Fritz • 5 piece tablebase allowed for end-game, 6 piece widely available
Computer chess ratings • SSDF – Swedish Chess Computer Association • Tests computer chess programs and produces a rating • 2012 “Deep Rybka 4 x 64” 3221 rating • Tested on x 64 2 GB Q 6600 2, 4 GHz
Algorithmic Considerations Board Representation • List of all pieces • 8 x 8 2 D array • 0 x 88 § 2 boards next to each other. Makes move-legality checks a simple AND with the hex number 0 x 88 • Bitboard § 64 bit sequence of bits. Series of bitboards. • Stream based • Huffman Encoding § More common chess positions (pawns/empties) stored with less bits
Main Search Types • Type A § Brute Force. Checks bad and trivial moves unnecessarily. • Type B § Quiescent Search – evaluate minimax game trees § Only a few moves are evaluated
Type B • Alpha-beta pruning widely used to reduce search space • Negascout – directional search algorithm to find minimax value of a node in a tree
“Tablebases” • Nalimov endgame tablebase. 5 or fewer pieces is solved. § USSR born programmer • 6 pieces is solved except some trivial cases such as 5 pieces versus 1 king • 7 pieces have been somewhat analyzed • All of these make certain assumptions to prune the branching possibilities. § Eg: Castling is no longer possible
Last Thoughts One last interesting note: It is estimated that doubling the computer’s speed adds only 50 -70 ELO to a given chess algorithm Heuristics are much better than brute force!
References • Digital computers applied to games'. n. d. AMT's contribution to 'Faster than thought', ed. B. V. Bowden, London 1953. Published by Pitman Publishing. TS with MS corrections. R. S. 1953 b • “Deep Blue”. IBM. http: //www-03. ibm. com/ibm/history/ibm 100/us/en/icons/deepblue/ • “The Last Man vs Machine? ”. Chess News. http: //en. chessbase. com/home/Tab. Id/211/Post. Id/4003504 • “Important Official Rules of the Kramnik versus Fritz match”. Chess Daily News and Information. http: //susanpolgar. blogspot. com/2006/11/important-official-rules-ofkramnik. html • Levy, David; Newborn, Monty (1991), How Computers Play Chess, Computer Science Press, ISBN 0 -7167 -8121 -2
References • Searching for Solutions in Games and Artificial Intelligence (1994) by Victor L. Allis • SSDF. Swedish Chess Computer Association. http: //ssdf. bosjo. net/ • Some images from Wikimedia Foundation • “Did a Computer Bug Help Deep Blue beat Kasparov”. Wired. com. http: //www. wired. com/playbook/2012/09/deep-blue-computer-bug/
- Mastering chemistry.com
- Mastering physics
- Mastering ao
- Mastering biology chapter 24
- Masteringandp
- Mastering self management
- Www.masteringbiology.com
- Mastering strategic management
- Mastering physics
- Mastering team skills and interpersonal communication
- Sacd mastering
- Doppler shift mastering physics
- Mastering physics
- Mastering phyiscs
- Mastering microfeatures
- Introduction to static equilibrium mastering physics
- Mastering strategic management
- Mastering microbiology login
- Mastering conflict management and resolution at work