Cepheus Poker Bot Can Play Heads Up Texas Holdem and Win Every Time, Say Inventors
Posted on: January 9, 2015, 07:49h.
Last updated on: January 12, 2023, 11:39h.
Cepheus, a computer program created by the Computer Science Department at the University of Alberta in Canada, has “solved” hold’em poker, its makers claim.
Or at least, the heads-up fixed limit variation thereof. And like all the best poker players, Cepheus is completely self-taught. The program, or bot, uses a completely new algorithm, known as CFT, which is able to analyze extensive-form games of incomplete information, such as poker, on a magnitude never before realized.
In layman’s terms, that means that Cepheus is able to play literally trillions of hands of poker against itself, learning and memorizing optimal moves as it goes, rendering it virtually unbeatable. In the words of its creators, it has created a game theory strategy so close to optimal that it “can’t be beaten with statistical significance within a lifetime of human poker playing.”
Of course, because poker is a game of incomplete information, it can never be said there is a “perfect” game theory strategy, merely an approximation of a perfect strategy, which is essentially a strategy that can’t be beaten by any other counter-strategy.
And the Alberta team think it’s cracked it.
24 Trillion Hands
“We’re not quite perfect, but we’re so close that even after a lifetime of playing against it, you wouldn’t know it wasn’t perfect,” said Professor Michael Bowling, whose team created Cepheus, and published its study in the journal Science this week.
“Even if you played 60 million hands of poker for 70 years, 12 hours a day, and never made any mistakes, you still wouldn’t be able to say with statistical confidence you were better than this program,” the study claims.
“Our model has spent two months playing poker again and again. It’s playing 24 trillion hands of Poker, every second for two months. That’s more poker hands than all of humanity, so in some sense it’s not surprising that it has developed the perfect strategy.”
Cepheus has been a long time in development, as the team have been engaged in this type of research since the nineties when it built its first bot, “Loki.” The team’s refined second attempt, known as “Poki” later provided the artificial intelligence for the video game, Stacked.
A later incarnation, “PsOpti,” powered Poker Academy, an AI training software program popular in the mid-to-late noughties. But Cepheus has blown its predecessors out of the water and the publication of the University of Alberta’s study is being hailed as a momentous day in the development of game theory.
Dealer Advantage Quantified
An interesting offshoot of the research is that the team have been able to quantify, for the first time, the the dealer advantage in heads-up limit hold’em, having had the opportunity to analyze it over trillions of hands.
“We actually can now prove that the dealer has an advantage of what we call ’88 millablinds’ per game,” explained team member Michael Johanson. “That’s .088 of a big blind per game.”
And the best bit is that you can now play against the best heads up-fixed limit poker player in the cosmos, and query its strategy if you dare, at poker.srv.ualberta.ca.
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Last Comments ( 3 )
This is LIMIT holdem. Funny how these articles tend to leave that out..
Cepheus is not unbeatable, as I have already beaten it twice out of five 100-hand matches. It may beat most on-line challengers because the web interface is horrible and that beats down a human's emotions. Worse, the queue to play is 50 users long, but only two can play at once. It used to be 4 players, but I noticed the server kept crashing and you would get summarily tossed out of your match. So, you end up waiting as long as two hours to get into a match and then might not get to finish it. There is also no indication of where you are in the queue, so you can easily get distracted and miss your 1-minute window to start playing, hours after you have finally gotten into the queue. It might help to pass the time, if you could see how the current players were doing. But no, this is all about Cepheus. Still, if you can hang in there, it is not a perfect poker player, and you can learn how to beat it fairly rapidly. Cepheus still has to get cards to win, and that remains a 50-50 proposition. Don't be intimidated by its betting strategy. Often, it doesn't have good cards, but keeps betting into them. You can bluff it and slow play it effectively, lose small and win big, just like playing a person.
I just beat Cepheus today, repeatedly. It took some work learning how to beat it, since limit heads-up is not a game I usually play. The website interface for Cepheus is also very annoying. It can take up to two hours to be let into a match, so be prepared to monitor your screen while doing something else. Then calm down and use most of the 60 seconds you are allowed to make your play. But, after losing my first two 100 hand matches, and badly, I figured out how Cepheus bets, and started winning hands, and then by my fourth match I was up for most of the 100 hands, at least by 300 points, and then ended the match still ahead. This morning I did it again in my 5th match with it. It clearly is not unbeatable. It is only as good as I am at this point, and I'm not all that great. I'm sure a professional could take it apart nearly every time without much thought. It's challenging enough, though, and fun getting in line to beat it.