Definition
Plain language
The full set of answers that should count as correct for a question.
As stated in the literature
The set of outputs a grader or verifier admits as satisfying a task; authoring it explicitly is materially harder than deciding membership for a single candidate.
Also called: acceptance regions
Why it matters: Writing down every acceptable answer in advance is much harder than judging one answer at a time, so graders built from a too-narrow acceptance region quietly punish correct work.
For example, if a question asks for a program that sorts a list, the acceptance region includes the version using one sorting method and the version using another, since both return the same correctly ordered list.
Heard on the show
“It's about one-shot materialization of an acceptance region when there's no compact rule available to restate.”Episode 233 — Why a Model Can Grade an Answer But Not Write the Answer Key