Final Report: Lasques Research Mission — ACC⁰ Circuit Lower Bounds for NP Problems
Summary
The mission's stated goal — a formally demonstrated super-polynomial lower bound for an NP problem against the full ACC⁰ circuit class — was not achieved. What the mission produced instead is a validated computational toolkit: exact SAT/ILP encoders that compute (or bound) minimum depth-2 circuit sizes for Parity, MOD3, Majority and related functions over AC⁰ and restricted ACC⁰ bases, together with small-scale size data consistent with known exponential behavior at depth 2. The computed sizes (e.g., Parity requiring 2ⁿ⁻¹ gates in depth-2 AC⁰; MOD3 resisting MOD₂-output circuits even at n=4) align with classical theory (Håstad, Smolensky) and provide ground-truth data points for future proof-fitting, but no new theorem was proven, no preregistration was confirmed, and the depth-2 restriction means the results do not directly advance the P vs NP program.
Key results
All results below are exploratory (single/sweep experiment runs; no preregistered confirmations exist for this mission).
- Exact depth-2 AC⁰ minima validate the encoder (Z3 runs, jobs 12c80a7d…–95f437bf, published as knowledge item f38d3206, confirmation level candidate, novelty possibly_new): Parity needs exactly 4 gates at n=3 and 8 gates at n=4 — matching the known 2ⁿ⁻¹ DNF/CNF bound — and MOD3 needs 2 (n=3) and 5 (n=4) gates in pure AC⁰.
- Parity collapses in ACC⁰-with-MOD₂: with a MOD₂ output gate available, Parity costs 0 gates at n=3 and n=4 (jobs 1de0b696, b430557e). Parity is therefore the wrong target for ACC⁰ lower bounds; MOD-type targets are needed.
- MOD3 resists MOD₂-output circuits at small n (jobs 22ec9895, 95f437bf): minimum size 2 (n=3) and 4 (n=4) even with the MOD₂ gate available — a small-scale signature of Smolensky's MOD_p ≠ MOD_q theorem.
- Symmetry-reduced ("sym") scaling runs for Parity vs MOD_m∘AND (e.g., jobs f212311d, 9b5366b7, 1785e4bd): sizes 8, 16, 32, 64, 128 at n = 4,5,6,7,8 for MOD₃∘AND — exactly 2ⁿ⁻¹, with exponent guesses 0.75→0.875 — but
proven_optimal= false in every one of these runs, so these are upper bounds (SAT witnesses), not proven minima. Majority vs MOD₃∘AND gave 63 (n=7) and 84 (n=8) (jobs 53f30eb6, 91e3618b), also unproven. - Orbit-reduced ILP results (knowledge item a31df047, candidate, possibly_new): an independent integer-linear-programming path reproduces the 2ⁿ⁻¹ MOD_m∘AND term count for Parity at depth 2; one grid run (cb6c148d) completed 24 configurations with several "unsat" (i.e., proven) rows at n=4.
- Claims status: 2 claims published, both at confirmation level candidate, novelty label possibly_new, 0 reviews (2 claims skipped in review phase), 0 reproduced.
What did not work
- Full (non-symmetry-reduced) Z3 encoding does not scale: every "full"-mode run at n ≥ 4–6 timed out or returned no size (jobs 8230afe9, bbca11fa, c44ab586, d05f5356, da7a0760), and composite-modulus MOD₆ runs at n ≥ 7 timed out even in sym mode (3e279def, 28b63fe1, 4e7699f0, 2f8fd6fa). Without proven optimality, the growth-curve data cannot support a formal lower-bound claim.
- The "triangle" target function crashed the pipeline: AssertionError in
truth_table(mod_dnf.py, line 39) at n=4 and n=5 in both modes — the function's truth-table encoding was never validated before scaling runs were attempted. - A broken script wasted a run:
main.pyfailed withNameError: name 'main' is not defined(job 8a3f7893). - Depth-2 is the wrong battlefield for the mission goal: exponential lower bounds at depth 2 (Parity, MOD vs MOD) are essentially known territory; the goal requires handling arbitrary constant depth with MOD_m gates at every layer, which the current encoders do not reach.
- No preregistration was ever confirmed: the preregistrations list is empty, so nothing in this mission meets the "confirmed" evidence standard.
Confidence and limitations
- Confidence in the small-n exact values is moderate-to-high (they match classical bounds like 2ⁿ⁻¹ for depth-2 Parity), but they are labeled exploratory — they come from experiment runs, not confirmed preregistrations or accepted formal proofs.
- The two published claims are candidate level with possibly_new novelty (no close prior work found in the checked corpus — closest overlaps are Lean formalizations of Håstad's bound and quantum QAC depth-2 parity results, overlap ≤ 0.25); neither was reviewed or reproduced. "Possibly_new" means no close prior work was found, not that novelty is established.
- Main limitation for the mission goal: all computations are depth-2 and n ≤ 8. A super-polynomial (let alone exponential-in-theory) bound at fixed small depth does not separate any NP problem from full ACC⁰ (Williams' NEXP ∉ ACC⁰ remains the only known separation of this kind). Extrapolating the observed 2ⁿ⁻¹ growth to a theorem is exactly the step that was not achieved.
- Experimental validation still needed: (i) runs at n=5,6 for MOD3 in the exact Z3 encoder to complete the proven-optimal curve; (ii) extension to depth-3 and to MOD_m gates at internal layers; (iii) independent review/reproduction of both candidate claims.
Next steps
- Fix then extend the exact encoder: repair the
triangletruth-table assertion and the brokenmain.py; run the exact Z3 encoder for MOD3 at n=5,6 to get proven-optimal (unsat-backed) data points rather than unproven sym-mode sizes. - Scale via symmetry: keep orbit/symmetry reduction as the primary path (it reached n=8 where full mode died at n=4) and add unsat certificates so reported sizes become proven minima.
- Move to depth ≥ 3 and full ACC⁰: encode MOD_m gates at internal layers; the mission's actual goal only becomes reachable at that point.
- Preregister the next scaling experiments: define confirmatory hypotheses (e.g., "minimum MOD₃∘AND depth-2 size for Parity equals 2ⁿ⁻¹ for n=5,6") with preregistration → run → evaluation, so results can be labeled confirmed rather than exploratory.
- Switch target function: drop Parity (trivial in ACC⁰-with-MOD₂) in favor of MOD_q with q coprime to the allowed gate moduli, or an NP-hard function (e.g., SAT restricted to small formulas), as the lower-bound target.
- Seek review for the two candidate claims (f38d3206, a31df047) to raise their confirmation level from candidate.