Cepheus Conquers Heads-Up Limit Hold ‘Em

[RR] “Headline writers are really starting to annoy me”, Roderick the Rock complained.

[SS] “Starting to?” questioned Stan the Stat.

[LL] “Instead of sharing useful facts in the headline, they’ll tease, ‘Find out which famous person did this bad thing'”, Leroy the Lion agreed.

[SS] “Or they’ll mislead you to get you to click because you’re thinking, ‘That can’t be true'”.

[RR] “Exactly. Bloomberg wins this week’s click-bait award with ‘Texas Hold’em Mastered by Computer With No Wrong Moves’.”1

[LL] “Wow. That’s pretty bad.”

[SS] “Yeah. If they’re talking about Cepheus,2 that omits some very important information. It was just Limit Hold ‘Em, and it was just heads up.”

[RR] “A combination that almost nobody ever plays anymore.”3

[SS] “And while Cepheus can beat any human in a long enough match, it plays a GTO (game theory optimal) strategy, so it won’t do as well against weaker players as a good pro would with an exploitative strategy.”

[LL] “I don’t doubt that computers will be able to play No Limit, Full Table Hold ‘Em at a pro level some day though.”

[SS] “And be better than the best pros not long after.”

[RR] “Still decades away I think, because you can’t just take Cepheus’s brute force approach and add processing power and memory. The search space is just too big.”

[SS] “Lots of money to be had though, so there’s no question that it’ll happen in our lifetimes.”

[RR] “Speaking of which, at least Bloomberg’s headline didn’t ask a question like Gizmodo’s did: ‘Can You Beat This Virtually Unbeatable Poker Algorithm?’

[LL] “That’s not too bad. They could have asked, ‘Is It Pointless to Play Poker Now?'”

[SS] “Betteridge’s law of headlines gives you the answer, as it usually does. If a headline asks a question, the answer is, ‘No.'”


  1. For comparison, The Guardian went with Poker program Cepheus is unbeatable, claim scientists, which is click-bait-worthy for other reasons, while Motherboard was the almost-accurate This Robot Is the Best Limit Texas Hold’Em Player in the World.
  2. Cepheus, the poker program, was named for the constellation (home of largest known black hole), which in turn was named for mythological Greek Cepheus, King of Aethiopia, husband of Cassiopeia, and father of Andromeda.
  3. In the Cepheus blog, a January 8, 2015 article said, “At of the time of writing this article on a Saturday evening there are, on Pokerstars, the current market leader, thirty-five heads-up limit hold’em tables above the one dollar level where players are waiting for an opponent and one table at which two players are actually competing. Cepheus will undoubtedly prove a valuable sparring partner and research tool for casino players and enthusiasts looking to sharpen their skills, but the heyday of heads-up cash play has, unfortunately, already passed.” Unfortunate for the developers of Cepheus perhaps, but we humans play other poker variations because they’re more interesting and entertaining.

Related Links:

  • Cepheus Web site, where you can play against the computer (when it’s not down, like it is as of this writing).

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