v0.20.0 — stage F: H¹-object construction + certified γ₂ ≥ −0.02 bracket
v0.20.0 — stage F: the UOR construction of the crux (H¹-object + FORCED dictionary) and the certified γ₂ ≥ −0.02 bracket
Pure Lean 4 (no Mathlib, no sorry, no native_decide), choice-free {propext, Quot.sound}, warning-free; CI green; honesty audit passes (1940 non-private proof-layer theorems audited).
The H¹-object and the forced dictionary
The v0.18.0 bridge carried ⟨Cₙ,Cₙ⟩ = −2λₙ as interface data. Stage F derives it: a genuine rank-4 Néron–Severi-style lattice (Square/WeilLattice.lean) whose vanishing cycle Δ−Γ is proven primitive, the H¹ carrier named by its universal property (Square/Cohomology.lean), self-pairing computed from the Gram. The gate ran on the constructed object and located the frontier (Square/Forced.lean): the forced signature is exactly λₙ > 0 ∀n = RH — it did not come out positive, so hodgeIndexHolds/liPositivityHolds stay none.
The certified bracket γ₂ ≥ −0.02 (the v0.18.0 open computational frontier, now closed)
Rgamma2_ge_neg002 (Analysis/GammaTwoBracket.lean) proves γ₂ ≥ −1/50 constructively, via discrete Euler–Maclaurin (no constructive integration) on a new Real "ring engine" (RAddNF + RMulNF):
sStep_decomp— the trapezoidal residuals_p = b²·C2 + b·R1 + R0as a free polynomial identity (both sides reduced to the same 7 canonical monomials, matched by an explicit choice-free permutation);C2_nonneg(C2 ≥ 0, trapezoid ≥ integral) — dissolved by the coincidencedPlusQ(0,p) = ½(1/p+1/(p+1))exactly;sStep_lower_tele→hSeq_tele→Rgamma2_ge_hSeq— a single telescoping per-step bound, summed, lifted to the limitγ₂ = Rlim g2SeqDyadic(one-sided Archimedean);gamma2_decide— one big-integer kerneldecide(≈3 s, depthT=3, denominatorD=10⁸).
Honest scope
This is a certified constant bound (evidence), not a positivity-of-all-λₙ (= RH) claim. Pos λ₃ remains open: λ₃ ≈ 0.0173 is a small difference of Θ(1) terms (λ₃^arith ≈ +1.22, λ₃^∞ ≈ −1.20), needing the full λ₃-formula numeric assembly. The crux fields stay none; RH stays OPEN.
See CHANGELOG.md for the full entry.