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Published byArabella McLaughlin Modified over 9 years ago
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Jeff Berkowitz pdxjjb@gmail.com
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Tonight’s Talk Why is poker an interesting problem? A bit about poker strategy A simple tournament bot A more interesting tournament bot Onward and beerward
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Before we begin … a word about “tells” Somebody always asks about Poker “tells” “Computers can’t read tells!” (etc.) Answer: tells are critical to success … if you’re making a movie. Seriously: tells are not a big part of poker. Questions about tells usually come from people who haven’t yet grasped what a deep intellectual challenge the game is.
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Characterizing Games Open Information Limited Information Deterministic Nondeterministic Chess Checkers Go … Battleship Minesweeper … Backgammon … Poker Stock market …
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Strategy (1) – Equity Basics You hold: 5 4 Board shows: J T 6 2 You believe your opponent has JJ or TT She bets. Should you call? It depends on the pot odds 4 of the 46 unseen cards give you a likely winner Pot odds must be 11 : 1 (or so) to call Limit Poker
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Strategy (2) – Controlling Equity You Hold: K T Board shows: K 7 5 Pot contains 8 bets [note: small bets] You bet your pair of kings [9 bets in pot] Turns out, player on your left holds 9 8 Your bet helped give him the odds to call You should have checked, hoping to raise Faced your opponent with calling 2 bets Limit Poker
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Deception (1) – Face Up Poker Imagine Hold’em with hold cards face-up We’ll say heads-up (2 players) for simplicity All equity decisions are certain Your turn: simulate a few million hands < 1 second on modern CPUs Model opponents as equally perfect Bet based on the simulation outcome Limit Poker
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Deception (2) – Your Hidden Cards Now imagine you get to hide hole cards But the other player still plays face-up ;-) You play the same “optimal” strategy And your opponent knows it (important) Your bet positive expectation Negative for them – so they will always fold So you must “sandbag” some of your hands Now defining “optimal” is harder Limit Poker
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NL Tourney Strategy (1) - Background In general, for both limit and no-limit … Pre-flop play is simpler, more formulaic Because there is less information to go on Post-flop play is harder More information available More time (flop, turn, river) More room for deception, application of skill, …
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NL Tourney Strategy (2) But in no-limit, post-flop play is optional All-in on the pre-flop no post-flop decisions! Creates worst possible equity position for others Only possible in no-limit Especially important [later] in tournaments “Advance of the blinds” Consequence: “Move-in” or “All-in” players Book “Kill Phil” [Rodman & Nelson 2005]
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Digression: Poker in Academia University of Alberta Poker Research Group Their work started long before the fad – 1995 Numerous papers on the internet www.poker.cs.ualberta.ca Excellent software (100% pure Java) Spinout company – Poker Academy The company is actually called “Biotools” Product has a plug-in API for bots, “Meerkat”
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Demo - KillPhilBot Implements “Kill Phil Beginner” strategy From ibid (“Kill Phil”, Rodman & Nelson) Modified with a slightly smarter postflop
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Rules, rules, lotsa rules A nontrivial rule-based bot gets hairy If this else if this then that else if the other thing… Tracing scattered throughout Must restart Poker Academy to change the rules Solution: separate behaviors from code “Rule” (not really) interpretation system “In the future, every programmer will have their own language” (me, 2008) Poker Rules Definition Language - PRDL
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PRDLBot (“Phil Purdle”) Express decision tree in PRDL Parse with JJTree / javacc Evaluate the parse tree for the action No code generation (although there could be) Advantages: Put tracing in the engine not the rules definition Change and reload without restarting PA Not fully implemented yet
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PRDL Example (1) stage = PREFLOP // all identifiers refer back to bot core { m > 30 // “when we have a huge stack …” { holeCards in [KPGROUP_1, QQ, KQs] // use of a list of expressions { toCall <= BLIND // or write "numberOfRaises = 0" { bettors = 0 // no limpers { action [BET, (bankroll / 6)] // another use of a list of expressions } : // “otherwise, there are limpers”; push all-in { action [BET, bankroll] } // CONTINUES NEXT SLIDE
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PRDL Example (2) : // otherwise, raised pot { numberOfRaises = 1 { action [BET, max[5 * raise, bankroll / 6]] } : // multiple raisers { action [BET, bankroll] } : // otherwise big stack, we don't have ultra-strong cards: we're done { action CHECK_FOLD // use of an expression that is not a list } : // Post-flop { //..... etc..... }
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PRDLBot Tour
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Bibliography (1 of 2) U of Alberta (CA) Poker Research Group: http://poker.cs.ualberta.ca/ http://poker.cs.ualberta.ca/ Scroll to Publications. Recommended there: http://poker.cs.ualberta.ca/papers/AIJ02.html http://poker.cs.ualberta.ca/papers/AIJ02.html Great online bot programming articles: http://www.codingthewheel.com/category/poker http://www.codingthewheel.com/category/poker Poker Academy software: http://www.poker-academy.com/ http://www.poker-academy.com/ http://forums.poker-academy.com/viewforum.php?f=3
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Bibliography (2 of 2) Best overall poker web site / book publishers: http://www.twoplustwo.com/ http://www.twoplustwo.com/ Recommended books from them: See http://twoplustwo.com/books.phphttp://twoplustwo.com/books.php Best for beginners and for learning basic strategy are Ed Miller’s books, Gettings Started in Hold’em and Small Stakes Hold’em: Winning Big with Expert Play. Best for learning tournament play are the Harrington and Robertie book series, Harrington on Hold’em (volumes 1 through 3, to be studied in order).
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Online Poker Early years (1990s – 2002) IRC, academic, first commercial sites Fad (2003 – 2006) TV with exposed hole cards, Chris Moneymaker Reality (2006 - ) UIGEA, bot suspicions No individual has ever been arrested or charged with any crime for playing poker online in the United States.
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Cheating at Online Poker General approach Write bot to Meerkat interfaces Test and debug to high level of skill in PA Emulate Meerkat on a commercial poker client Consider Omaha 4 hole cards, must play 2 Like playing 6 Hold’em hands simultaneously Often played for a split high/low pot (12 hands) Computer advantage is maximized
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