Wednesday, January 21, 2015

Playing Cepheus

A short follow-up regarding Cepheus, the heads-up fixed-limit hold’em playing program developed by the Computer Poker Research Group at the University of Alberta I was writing about yesterday -- i.e., the program that is said to have essentially “solved” heads-up LHE insofar as (the researchers claim) “a human lifetime of play is not sufficient to establish with statistical significance that the strategy [employed by Cepheus] is not an exact solution.”

I mentioned how they’ve put Cepheus online for the curious to play against. Today after queueing up for a long time I managed to get a game against the program. We played 100 hands of 10/20 LHE, after which I managed to finish up 105 units -- just about five big bets.

I ran hot early on, so hot it almost seemed like things were rigged in my favor as I built up a lead of over 250 through the first 30 hands. Then things evened out between us and after 49 hands we were dead even, and for a hand or two after that I was down briefly. But I won three big pots in a row to zoom back up over 200, and ultimately never lost the lead again.

I played tight-aggressive throughout, becoming a little more conservative during the last dozen hands or so as I wanted to preserve my lead. Both Cepheus and I were mindful of position, with Cepheus raising almost every single button and folding otherwise (i.e., never limping). Meanwhile I also mostly raised or folded my buttons (folding more than Cepheus did), though I limped occasionally, too.

Cepheus would three-bet me fairly often before the flop when I did raise, and probably bet when checked to around 80-90% of the time (I don’t have a log of the hand histories, so can’t say for sure). After about 75 hands I had just begun to become aware of the fact that Cepheus hadn’t seemed to have check-raised me on either the turn or river, then the program did it twice within just a few hands, both times successfully earning extra bets as a result.

In the first case I was playing from the button with K-7-offsuit with the king of clubs, and the flop had come all clubs with the ace to give me a nut flush draw. Cepheus check-called me there, then a king fell on the turn and that’s where Cepheus check-raised me. The river was a blank, and Cepheus won the hand with K-Q.

The second instance also involved Cepheus connecting on the turn -- that’s a screenshot of that hand above (click to enlarge). I also managed to check-raise a couple of turns after making hands to get extra value.

Obviously the tiny sample established practically nothing regarding either Cepheus or myself. I will admit that toward the latter part of the session I felt my attention flag just a touch, enough to remind me of the difference between myself and my non-human competitor. If we’d gone on, say, to play 1,000 hands or more I imagine it would have been very difficult for me to continue to make correct decisions (not that all of the ones I made were correct).

If you happen to play Cepheus, let me know how it goes and what impressions you get from the program.

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3 Comments:

Blogger joe mamma said...

I played cepheus 4 times my results:
+710
-180
-175
-375
I won big the first time and lost the next 3 for a net of -20.
I've played a lot of poker but not a lot of heads up limit poker. I think this bot is beatable I'd like to see the results of some good players against it.

1/26/2015 4:25 PM  
Blogger Steve said...

I have beaten Cepheus repeatedly in the 100-hand matches offered. Its algorithm cannot contend with the luck of the draw, no matter how aggressively it bets; making you think it has cards, when it actually doesn't. Match its aggressiveness, don't fold, and you will win just as often as it does; so again, it just comes down to getting cards. At best, Cepheus is a fair game for a very good poker player, who has a good idea of heads-up odds -- roughly the 90:10, 80:20, 70:30, 60:40, and 50:50 holds. And you don't have to have computer precision in these probabilities, simply because you don't know what the other player holds. All you have to keep in mind is that in two-player poker, if nobody looks at their cards, the odds start at 50:50. When you then look at your cards, you bet accordingly, based on where you think you stand. Because you still don't know the other player's cards, and he doesn't know yours, a player can only know their odds potential, based on their own hold cards. The law of large numbers, (repeatedly playing and expecting statistical convergence of results), only loosely applies, because there exists a real probability of being wrong -- neither player has perfect knowledge. For this logical reason alone, the "unbeatable" claim is incorrect and outrageous, and humans are proving just that the more they play Cepheus.

3/12/2015 8:32 PM  
Blogger Steve said...

I have beaten Cepheus repeatedly in the 100-hand matches offered. Its algorithm cannot contend with the luck of the draw, no matter how aggressively it bets; making you think it has cards, when it actually doesn't. Match its aggressiveness, don't fold, and you will win just as often as it does; so again, it just comes down to getting cards. At best, Cepheus is a fair game for a very good poker player, who has a good idea of heads-up odds -- roughly the 90:10, 80:20, 70:30, 60:40, and 50:50 holds. And you don't have to have computer precision in these probabilities, simply because you don't know what the other player holds. All you have to keep in mind is that in two-player poker, if nobody looks at their cards, the odds start at 50:50. When you then look at your cards, you bet accordingly, based on where you think you stand. Because you still don't know the other player's cards, and he doesn't know yours, a player can only know their odds potential, based on their own hold cards. The law of large numbers, (repeatedly playing and expecting statistical convergence of results), only loosely applies, because there exists a real probability of being wrong -- neither player has perfect knowledge. For this logical reason alone, the "unbeatable" claim is incorrect and outrageous, and humans are proving just that the more they play Cepheus.

3/12/2015 8:33 PM  

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