Definitions for the oracle-ceiling diagnostic (scripts/oracle_ceiling.py; design in
ORACLE_CEILING_DIAGNOSTIC.md). Together these metrics answer one
question: is there enough routable complementarity in the model pool that a better router could
beat the best single model, or is the ceiling so close to best-single that only the pool matters?
Every metric derives from p[q, m] — the estimated probability that model m solves query q,
averaged over K independent samples (p_hat in code).
mean_q max_m p[q, m], winner's-curse-debiased by a split-half cross-fit. The best an ideal
query-conditional deterministic router could achieve: for each query it picks the single model most
likely to solve it. This is the honest, routing-achievable ceiling. It is floored at
best_single_crossfit — a perfect router can always fall back to the best fixed model, so the true
oracle is mathematically >= best_single.
routing_oracle - best_single_crossfit. How much accuracy a perfect router could add over the best
fixed model. It is measured from the cross-fit baseline, not the full-K best_single. Both
terms must share one estimation regime, or the difference is contaminated: an oracle built on the
held-out half compared against a full-K best-single yields a spurious negative headroom on
otherwise-identical pools. Read the verdict off this metric's bootstrap CI, never the point estimate.
(trinity - best_single_crossfit) / (routing_oracle - best_single_crossfit). The fraction of the
real, achievable headroom the trained router actually captures. It is NaN when the denominator
is <= 1e-9 (no achievable headroom -> the ratio is undefined, not zero), so callers must guard
on the headroom CI before trusting it. Numerator and denominator both use best_single_crossfit;
mixing in the full-K best_single can make the denominator negative and silently flip the sign — a
router below the baseline would then report a large positive capture.
| Term | Definition | Meaning |
|---|---|---|
best_single |
max_m mean_q p[q, m] (full-K) |
Best fixed single model; the per-model reporting baseline. |
best_single_crossfit |
best_single evaluated on the held-out cross-fit half |
The routing baseline that routing_headroom and router_gap_closed are measured from; shares the oracle's estimation regime. |
routing_oracle_naive |
mean_q max_m p[q, m] (no cross-fit) |
Upward-biased oracle (winner's curse on the max). Reported only to quantify the bias against routing_oracle. |
clairvoyant_any |
mean_q (1 - prod_m (1 - p[q, m])) |
Probability that some model solves the query. An optimistic upper bound a single-pick router can not reach — it measures noise, not routable opportunity. |
unroutable_noise |
clairvoyant_any - routing_oracle |
Apparent gain that exists only from luck / nondeterminism and is not capturable by routing. |
Every metric above is emitted by the analyzer for a collected correctness matrix:
python scripts/oracle_ceiling.py --analyze experiments/final/oracle_matrix_math500.jsonThe report's point_estimates block carries best_single, best_single_crossfit,
routing_oracle, routing_headroom, and unroutable_noise. router_gap_closed appears under the
trinity block when a per-query TRINITY correctness file is supplied via --trinity-per-query. The
verdict (pool-bound / router-bound / near-ceiling) is read off the bootstrap CIs, per
ORACLE_CEILING_DIAGNOSTIC.md section 6.