AI-led Lean proof settles a seven-vertex unit-distance case

For every simple graph G on seven vertices, either G or its complement has an injective unit-distance representation in Euclidean R³, where every edge has length one and nonedges are unconstrained. This proves the d=3 case of Frankl–Kupavskii–Swanepoel Problem 2; their general 2d+1-vertex question remains open. Combining with the published lower bound gives f_D(7)=3, although the lower bound is outside the formal target.

Sources for this record

What was already known

Frankl, Kupavskii and Swanepoel asked the general 2d+1-vertex unit-distance question. Their lower bound gives the matching dimension when d=3.

AI involvement AI-led

Dishant Shah chose the d=3 target and signed the statement. AI agents wrote the central graph proofs and integrated the Lean development; Claude Opus 5.5 managed the work and made mathematical fixes. No named human explanation of the graph-classification proof is documented.

The public run log metadata attributes most central proof leaves and the accepted ten-edge theorem to AI agents; the human owner fixed the target and statement, and the managing AI integrated and repaired work.

Importance Modest

The proof settles the seven-vertex case of a broader open dimension question.

Limitations

Priority for the seven-vertex case against earlier proofs is unestablished; Shah’s sign-off checked the target statement, not the full proof.

Technical verification Formal (Lean 4 with Comparator and NanoDa)

The cited development reports Lean and NanoDa acceptance of questionAt3 via Comparator; statement fidelity was separately checked and signed by the owner. This review did not rerun the build.

Formal checking

Kernel checks, Comparator statement match and standard-axiom audit

Checker
Lean 4 and NanoDa kernels, reported in repository Comparator record
Scope
FKSProblem2.Palomar.target = questionAt3
Basis
Reported by the linked checker
Evidence source

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

Human understanding Few

The owner’s sign-off documents statement understanding, not explanation of the central graph-classification and placement proof. The README outline and agent review do not establish a human explanation; Few is the evidence default.

Correction and publication history