Parity of k-differentials in genus zero and one

Dawei Chen, Evan Chen, Kenny Lau, Ken Ono, Jujian Zhang

For odd k≥3 and integers n with gcd(n,k)=gcd(n+1,k)=1, AxiomProver found a Jacobi-symbol reformulation and the floor-sum identity N_k(n)=F_k(n+1)−F_k(n). The authors combine that identity with classical Jacobi facts to establish the parity formula N_k(n)≡⌊(k+1)/4⌋ mod 2 and make the earlier genus-zero and genus-one k-differential formulas unconditional.

Sources for this record

What was already known

Chen and Gendron’s spin-parity classification was conditional on their number-theoretic Conjecture A.10.

AI involvement AI-autonomous

The authors report giving AxiomProver the conjecture without references, geometry or method hints. It found the key reduction and later formalized the identity; human authors completed and explained the argument and geometric application.

The central reformulation and missing reduction were obtained from the conjecture alone, without method hints or proof, before the authors' exposition and geometric application.

Importance Notable

Supplies the missing reduction that removes the conjectural condition from the stated spin-parity formulas.

Limitations

The reported Lean proof covers the floor-sum identity, not the Jacobi-symbol bridge or geometric corollaries. No explicit full human proof check of all steps is documented.

Technical verification Partial

Lean 4.26 reports a complete check of Lemma 2.5's floor-sum identity, but the Jacobi-symbol reduction from that identity to the parity conjecture and the geometric consequences are not formalized. The paper explains those steps; an explicit complete human proof check is not documented.

Formal checking

Formal proof of main_theorem matching the displayed counting and floor-sum definitions; source-reported.

Checker
Lean proof assistant through AxiomProver's solution.lean, as reported by the authors
Scope
Lemma 2.5: N_k(n) = F_k(n+1) - F_k(n) for odd k >= 3, under the stated coprimality assumptions
Basis
Reported by the linked checker
Evidence source

Checking a formal statement does not establish that it matches the original problem.

Human understanding Full

The authors explain the Jacobi-symbol reformulation, the floor-sum identity, and how classical number theory completes the stated parity formula in Section 2.

Correction and publication history

2026-10-18 · publication

Supplies the missing reduction that removes the conjectural condition from the stated spin-parity formulas.

Read this published revision