Claude formalizes an alternative Hadamard border argument

Claude agents devised an integer proof route for the s=1, index-two clauses of Theorem D in Jones’s Hadamard border note, replacing its rank and positive-semidefiniteness route. The formal development checks those Theorem D clauses.

Sources for this record

What was already known

JD Jones’s note had already stated and proved the border theorems. Goethals–Seidel constructions, other border cases, and Hadamard matrices of orders 20 and 52 were known before this formalization.

AI involvement AI-centered

Jones supplied the source note and selected the scope. Claude Fable and Opus agents chose the alternative proof route and formalized it; Jones says he did not mathematically review that derivation.

Claude supplied a distinct central mathematical derivation of the already stated Theorem D clauses; the theorem statement and prior proof came from Jones.

Importance Modest

Adds a machine-checked alternative derivation for a bounded part of an existing theorem package.

Limitations

The formal check does not cover the source note’s whole Hadamard program. No independent human mathematician comparison with Jones’s proof is documented, and the protected multi-kernel comparison was not reported for this code version.

Technical verification Formal (Lean 4 kernel with transitive axiom audit)

The cited disclosure reports a successful local Lean build and transitive axiom audit for the 26 compared theorems. This checks the formal integer route on the stated clauses, not the unformalized Theorem C clauses, census, or source-fidelity/priority claims. Comparator and NanoDa had not run at this commit.

Independent checking

Local build, kernel proof checking, and transitive audit limited to standard Lean axioms

Checker
Lean 4 kernel and project axiom-audit script
Scope
The 26 compared formal statements, including Theorem D clauses D-a through D-e
Basis
Reported by the linked checker
Evidence source

Human understanding Few

Default for missing human explanation of the alternative integer proof: Jones disclaims mathematical work on the formalization and reports only AI reviews.

Correction and publication history

2026-10-18 · publication

Adds a machine-checked alternative derivation for a bounded part of an existing theorem package.

Read this published revision