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.