ARC White-Box Estimation Challenge 2026 · Public companion

What one 332-submission campaign can teach us

A regime-aware map of depth-32 estimation: exact identities, deterministic cubature, compute-aware algebra, negative results, and the limits of public-score inference.

Single-participant case studyNot a field censusNot a private-rank forecastEvidence cutoff: 11 Aug. 2026

Start with the unit of evidence

The campaign is large, but its counts answer different questions. Collapsing them would turn an audit trail into a misleading headline.

Interpretation boundary. These are one participant's submissions and local records. They illuminate mechanisms and evaluation practice; they do not describe every participant or predict the fresh private re-evaluation.
332participant submission attempts
238 / 94currently graded / failed
212version-labeled workspaces
14,522numeric record occurrences, not hypotheses
S=1Ni=1NeiciS = (1/N) Σᵢ eᵢcᵢ. Lower is better. It is a mean of per-MLP products, not the product of two global means.
A cumulative line rises from 1 to 332 submissions between July 26 and August 10. Each submission also appears in one of eight analytical campaign rows. Circles are currently graded and crosses are currently failed; runtime colors are final recorded labels.
Figure 1. The full campaign timeline. Campaigns are reproducible analytical groupings, not organizer categories. Final runtime labels may differ from the evaluator first seen at upload time.

The runtime changed in stages

A GitHub release time, a first observed production evaluation, and an official announcement are different events. The analysis retains each rather than forcing them into one change point.

30 Jul., 23:14 UTC

FlopScope 0.10.0 released on GitHub.

31 Jul., 03:06 UTC

WhestBench 0.14.0 released on GitHub.

3 Aug., 04:46 UTC

First final-runtime evaluation observed in this reconstruction.

3 Aug.

AIcrowd publicly announced the new runtime, cost-model fixes, and re-evaluation [official update].

Forty-five paired lines connect earlier and final numeric scores. Thirty-three worsen, eleven are effectively unchanged, and one improves. A separate bar shows nine earlier numeric scores removed as current combined-budget failures.
Same-ID comparisons are stronger than cross-submission correlation, but they still cannot isolate one causal rule or server change.
Six bars show 56 compute-budget, 26 smoke-test, 6 setup, 3 incomplete-evaluation, 2 scoring, and 1 format failure among 94 current failures.
Failed submissions are unranked outcomes; no synthetic accuracy score is assigned to them.

Explore the graded score-compute surface

The interactive plot contains all 238 currently graded rows with exposed positive score and compute. Filter by analytical campaign; keyboard and screen-reader users can use the synchronized top-record table.

Adjusted score versus mean compute utilizationA log-log scatter of currently graded submissions. Lower adjusted scores are better. Use the campaign selector to filter.
Lowest adjusted scores in the current filter
SubmissionScoreComputeCampaign
The upper panel is a log-log score versus compute plot for 238 graded submissions. A separate lower strip places 94 failed submissions by category, so failure is never encoded as a score.
Static companion view. The plot is descriptive; compute and campaign membership alone do not establish causality.

The campaign narrowed from many hypotheses to one lineage

Broad mechanism search

Analytic closures, learned correctors, covariance compression, multifidelity controls, conditional integration, MLMC, QMC variants, and native-kernel paths were tested against explicit gates.

Structured statistical path

One long Sobol stream with exact antipodal pairing beat eight shifted replicates by 7.04% in a 500-network, three-seed screen. Stronger LMS scrambling regressed.

Deterministic cubature sweeps

Row counts, rotations, frequency packs, pilot sizes, and thresholds were treated as configurations inside one broad design family, not independent theories.

Exact work reduction

The late frontier held raw MSE near 1.92e-7 while Walsh-Hadamard, antipodal, and Strassen-Winograd rewrites lowered metered compute.

A descending running-minimum curve follows 69 record-setting submissions from about 8.35e-7 on July 26 to 8.70e-8 on August 9. Points are colored by recovered method campaign.
Temporal order is not a causal decomposition. Neighboring variants, exact source inspection, repeat artifacts, and local checks carry more weight.

Case study: #326948 separates identities from approximations

The final estimator combines a structured directional design with exact metered algebra. It is not “all exact”: the pilot masks, live-column pruning, finite cubature, pilot-dead zero fill, and pilot-row reuse are approximation choices.

𝔼[f(X)]=𝔼[R]𝔼[f(U)]For X=RU and a bias-free positively homogeneous ReLU network. E[R] = √2 Γ((d+1)/2) / Γ(d/2).
  • Exact identity

    Radial-angular split

    For X=RU and a bias-free positively homogeneous ReLU network f, f(RU)=R f(U). Estimate the sphere expectation and multiply by E[R].

  • Deterministic construction

    Structured directions

    Use a weighted Kerdock/MUB carrier. A numerical certificate checks its quantized low-order moment identities; this does not prove exactness for the deep nonlinear integrand.

  • Approximation

    Pilot routing

    Load the shipped 1,152-row pilot (512 rotated axis rows and a 640-row code supplement). Keep a coordinate when it fires on more than two pilot rows.

  • Exact rewrite

    First-layer factorization

    Factor each Kerdock coset into sign, Walsh-Hadamard, and diagonal operations; replace dense layer-0 multiplication with one 256-cubed product plus FWHTs.

  • Exact identity

    Antipodal reuse

    Compute one side of each +/- pair and recover the mirror using ReLU(-y)=ReLU(y)-y, with an additional transform for the layer-1 mirror.

  • Approximation

    Packed deep pass

    Propagate 64,896 main code trajectories through layers 2-30 after removing pilot-inactive columns; combine them later with the 640 pilot code rows and 512 axis rows to recover the weighted 66,048-point estimate.

  • Exact arithmetic plans

    Metered planner

    For each live matrix shape, compare dense, padding, peel-k, peel-n, and peel-both plans across Strassen-Winograd depths; all fringe decompositions are exact.

  • Mixed

    Final split and recycling

    Combine an always-on linear mean, a row-wise ReLU path for kinked units, zero-fill pilot-dead units, and reuse the pilot's 512 axis rows plus 640 code rows in the weighted final mean.

Exact implementation record correction. The submitted implementation loads a 1,152-row implementation asset: 512 rotated axis rows followed by a 640-row code supplement. Its live-mask condition is count > 2. Later loose source used a different pilot path and is not evidence for the submitted artifact.
8.699e-8official adjusted score
1.920e-7final-layer MSE
45.50%mean compute utilization
0 / 50public MLP failures

Five byte-identical repeats span 8.69896e-8 to 8.71106e-8, a 0.139% range relative to their mean. That bounds repeat noise for this artifact under the final captured public regime; it does not bound fresh-network uncertainty.

Negative results are the reusable part

Each row is phrased as question → controlled observation → boundary. A boundary applies only to the measured implementation and evaluation surface.

QuestionControlled observationReusable boundary
Can Gaussian moment propagation replace sampling at depth 32?Final-layer MSE was 7.5133e-5 at width 256, about 411 times the contemporaneous 1.83e-7 reference; error accumulated with depth.Not competitive alone in this regime; useful as a mechanism and scaling diagnostic.
Does covariance spectral concentration justify truncation?Effective rank fell from about 164 to 2.8, but ranks 8-64 left relative error nearly flat near 3.4e-2.Low effective rank did not imply a safe low-rank covariance approximation.
Can the omitted diagonal residual image be sketched?A W^T diag(d) W sketch improved relative L2 error from 1.29e-2 to 6.9e-3 at r=64, k=16.A positive component result, but the estimated full-score effect was only 1.7-3%.
Do stronger digital scrambles automatically improve QMC?Two LMS-scrambled banks regressed by 3.25% and 5.88% in the controlled local screen.Scramble quality was integrand-specific; sophistication alone was not a promotion criterion.
Can active-subspace stratification help?The q2 arm improved 10.09% over 32 networks x 3 observations, but its clustered interval crossed zero.Promising signal, insufficient generalization evidence.
Can exact conditional integration remove variance cheaply?The best ray direction removed 20.64% of variance but required roughly 8,000-10,000 regions and 6-7 seconds per ray.Mathematically effective, computationally infeasible in the measured implementation.
Do structural or learned controls produce a large gain?Most measured gains were below 0.1-3%; honest cross-fit variants sometimes regressed.The tested control families did not clear their predeclared cost-normalized gates.
Does exact MLMC telescoping guarantee favorable economics?The pathwise identity held, but projected raw MSE was 5.26e-6, more than 11 times the target.An exact identity can still have an unfavorable level-variance budget.
Can lower precision or VNNI supply the missing factor?The tested capability marker did not fire: the evaluated environment did not expose AVX-512 VNNI to that submission. The tested block-int8 path took 7.1686 s versus 0.18745 s for FP32 (38.24x slower) and 24.98x the separate 0.287 s residual-time target.This specific VNNI path was not exposed to the tested submission, and this block-int8 implementation failed its measured throughput target despite acceptable numerical fidelity.
Does higher cumulant order retain its advantage with depth?Corrected sweeps had k3 beat k2 at every tested depth, but the advantage decayed from 35x at depth 8 to 1.8x at depth 32; k4 ran out of memory at depth 24 and above on 48 GB.Higher order still helped, but depth and memory bound the approach.

The public 50 cannot certify private ordering

After hundreds of submissions, the public suite is selection data. Public-only resampling can characterize instability on those same networks; it cannot manufacture fresh MLPs or seeds.

Fifty paired public-MLP scores for submissions 326948 and 327292 lie close to equality. Submission 326948 is lower on 33 networks and 327292 on 17. The paired bootstrap interval for their mean ratio crosses zero effect.
Public-only candidate comparison: Pearson r=0.9773; bootstrap estimate for #327292/#326948 minus one is +2.335%, interval -0.560% to +5.193%. This supports cautious diversification, not certain superiority.
No rank forecast. The official selection notice states that the conclusive comparison comes from a newly generated post-Phase-1 private re-evaluation with private seeds. Public position does not carry over.

Download the evidence behind every chart

These buttons reconstruct embedded byte-for-byte copies, so the page remains useful offline. The adjacent package also contains chart-level CSV/JSON and SVG/PNG assets.

Reproducibility boundary

The public timeline keeps method and outcome rows while excluding internal provenance handles. The 332-row grader appendix keeps current status, score fields, failure messages, runtime labels, method labels, and public submission URLs. Source packages, authentication material, and other participants' code are not embedded in this public page.

References

  1. ARC White-Box Estimation Challenge 2026. Official challenge page and current framing.
  2. Phase 1 runtime and deadline update (3 Aug. 2026). Official FlopScope 0.10.0 / WhestBench 0.14.0 update and re-evaluation guidance.
  3. Phase 1 selection and Phase 2 launch date (10 Aug. 2026). Official fresh-suite/private-seed selection guidance.
  4. ARC/AIcrowd technical-writeup guidelines. Official guidance used to structure the mechanism, evidence, ablations, reproducibility, and disclosure.
  5. Wu et al., Mechanistic Estimation for Wide Random MLPs. Primary companion paper; analytic/cumulant context and challenge motivation.
  6. ARC: Mechanistic estimation for wide random MLPs. Official research overview and limitations.
  7. AIcrowd/whest-starterkit. Official estimator contract, validation, and metering implementation.
  8. aicrowd/arc-whestbench-public-2026. Official public dataset repository and provenance.
  9. Can et al., Kerdock codes and mutually unbiased bases. Primary mathematical background for Kerdock/MUB structure.
  10. Klappenecker and Rotteler, Mutually unbiased bases are complex projective 2-designs. Primary design-theoretic context.
  11. Stewart, Structure-Aware Estimation (SOX #319341, 27 Jul. 2026). Public prior art for pilot reclassification and dead/on/kink routing.
  12. Pepper, arc-whestbench-higher-moments-2026. Used offline as labels for a pre-submission cumulant-model experiment and falsification; not loaded by #326948.
  13. Pepper, whestbench-relu-mlp-moments-10k. Used offline for width/depth, closure, and estimator-screening experiments; not loaded by #326948.
  14. Delsarte, Goethals, and Seidel, Spherical codes and designs. Primary source for the spherical-design lower-bound comparison.
  15. ARC, A Mike's-eye view of ARC's research. Sponsor research agenda and the broader mechanistic-estimation objective.
  16. pluto, Phase 1 Write-Up: A Modern Approach. Inspiration for the persistence side of the multi-model workflow; not technical evidence for the estimator.

LLM disclosure

OpenAI Codex and Anthropic Claude assisted with orchestration, code generation, evidence indexing, data analysis, figure production, and drafting; GLM supplied an additional proofreading and review pass. Human direction determined questions, promotion/kill decisions, candidate selection, and publication scope. Model agreement was not treated as validation: outputs were challenged by other models and then checked against preserved official grader records and contemporaneous participant records. Reconstructed labels remain distinguished from directly checked submitted configurations.

AIcrowd participant pluto's “keep going” account inspired the persistence side of this workflow. My variation added a friendly Simpsons-style pile-on: Codex, Claude, and GLM were asked to challenge one another's claims, with the recorded results deciding disagreements.

Rob Schneider saying You can do it
pluto as Rob Schneider: “You can do it!”
A cartoon crowd in a friendly fight
Brad's version: keep going, then make the AIs challenge each other.