In addition, to combat fatigue, the humans are allowed to take breaks whenever they want to, and can take as long as they like to play a hand.
"The humans are very careful about their sleep hygiene and their eating and all of that," Sandholm says. "These are real professional athletes. They have been playing better now than they were in the beginning. Their play has improved during the match so far."
With seven days played as of this writing, Libratus is ahead in chips against all four players, and is cumulatively ahead by more than $470,000. Rivers Casino is streaming the match live via Twitch for the duration.
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