Definition
Plain language
A trusted source of the correct answer used to grade or compare attempts — reliable but usually expensive to consult.
As stated in the literature
In agent and verification settings, a high-fidelity ground-truth checker or reference solution treated as authoritative; e.g., the expensive final verifier in Bayesian control, or hand-built best-possible solutions used as a ceiling in computer-use benchmarks.
Why it matters: It provides a dependable measure of correctness, but because consulting it is costly, systems must use it sparingly and lean on cheaper checks in between.
For example, a final hand-built reference solution might be consulted only at the very end to confirm whether an agent's answer was truly correct.
Heard on the show
“At the top there's an oracle.”Episode 245 — Fifteen Models Ran Football Clubs for Twenty Years, and Size Didn't Decide It