An AI Poker Bot Has Whipped the Pros
An
AI Poker Bot Has Whipped the Pros
Jamie
Condliffe, MIT Technology Review, January 31, 2017
Humans
have been bested by a computer in yet another game once considered too
difficult for artificial intelligence to master.
Over
the past three weeks, an AI poker bot called Libratus has played thousands of
games of heads-up, no-limit Texas hold’em against a cadre of top professional
players at Rivers Casino in Pittsburgh. And it beat them all.
Our
own Will Knight recently explained why victory for Libratus, which was built by
a pair of researchers at Carnegie Mellon University, would be such a big deal:
Poker
requires reasoning and intelligence that has proven difficult for machines to
imitate. It is fundamentally different from checkers, chess, or Go, because an
opponent’s hand remains hidden from view during play. In games of “imperfect
information,” it is enormously complicated to figure out the ideal strategy
given every possible approach your opponent may be taking.
In
heads-up, no-limit Texas hold’em, then, it's virtually impossible, for there is
no single correct play. Instead, the AI must use game theory to calculate
optimal plays given the uncertainties.
In
the end, it wasn’t even close: Libratus made off with $1.8 million in chips,
while all four of the pros ended up with a deficit. Artificial intelligence has
never beaten top players at a game so lacking in information as no-limit Texas
hold’em. Like DeepMind’s Go victory before it, then, the win is a seminal
moment for the machine learning community.
But
what was it like for the humans to play against? “It’s slightly
demoralizing," Jason Les, one of the professionals, told the Guardian.
"If you play a human and lose, you can stop, take a break. Here we have to
show up to take a beating every day for 11 hours a day. It’s a real different
emotional experience when you’re not used to losing that often.”
Daniel
McAulay, another professional, explained to Wired that the AI's ability to hold
different plays in its memory made it stand apart from human contenders. “It
splits its bets into three, four, five different sizes,” he explained. “No
human has the ability to do that.” Still, don’t feel too badly for the
vanquished humans: despite losing, they're divvying up $200,000 between
themselves based on how well they did during the tournament.
For
the AI, though, this is just the start. Having proven that it’s possible to
beat the professionals at their own game, there is now a very clear next
challenge to chew on: multi-player no-limit Texas hold’em. But the game theory
used in the current software falls down when there's more than one opponent,
and it's not clear what technique to use instead.
Still,
given the progress machine learning is currently making, and the fact that
other AI poker bots are also being developed, that seemingly impossible
challenge may not remain impossible for long.
(Read
more: Bloomberg, Wired, The Guardian, “Why Poker Is a Big Deal for Artificial
Intelligence,” “Poker Is the Latest Game to Fold Against Artificial
Intelligence,” “Five Lessons from AlphaGo’s Historic Victory”)
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