Definition
Plain language
Poker played one-on-one, just two players at the table.
As stated in the literature
In poker, a two-player (one-versus-one) format; heads-up no-limit Texas Hold'em is the standard testbed for poker AI such as Libratus and PokerSkill.
Also called: heads up
Why it matters: It matters because the one-on-one setting is the cleanest stage for testing an AI's strategy under hidden information.
For example, when a poker tournament narrows down to its final two players, they play heads-up until one has all the chips.
Heard on the show
“But sit it down to actually play heads-up no-limit Texas Hold'em against a top solver, and it gets absolutely crushed.”Episode 100 — How a Prompt Wrapper Lets a Frontier Model Play Poker Like an Expert