AI-assisted Lean proofs give a hard-sphere volume identity and bound

For k≥2 in any positive integer dimension, the magnitude of the kth hard-sphere Mayer coefficient, multiplied by k!, equals a sum of no-broken-circuit region volumes over spanning trees. In dimension three, each tree-region volume is at most (17/32)^ν(T)κ^(k−1), where κ is unit-ball volume and ν(T) is the largest packing of disjoint ordered forks a<b<c with tree edges ab and ac.

Sources for this record

What was already known

Classical broken-circuit graph identities and earlier tree-graph methods existed. The new work connects the pointwise identity to measurable volumes and supplies a three-dimensional per-tree suppression bound.

AI involvement AI-centered

ukiyois set the direction and reviewed the scope. An AI coding agent using GPT-5.6 Luna completed the orientation-aware factorization and the 17/32 per-tree bound.

The source assigns the retained factorization and fork bound to an AI handoff under human direction.

Importance Notable

The results add a checked measure-theoretic bridge and an explicit geometric bound for a hard-sphere expansion.

Limitations

These statements do not establish convergence of the full series or strict positivity. Earlier AI fact-chain results are separately credited, and no independent human proof check is documented.

Technical verification Formal (Lean 4/Mathlib kernel and axiom audit)

Lean reportedly proves both selected statements and reports an axiom audit.

Formal checking

Lake build, Challenge/Solution compilation and axiom printout

Checker
Lean 4 kernel
Scope
PalomarHS.main_result and PalomarHS.nbc_region_real_volume_le_fork_factor
Basis
Reported by the linked checker
Evidence source

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

Human understanding Few

No named human explanation of the orientation-aware factorization is documented; Few is the evidence default.

Correction and publication history

2026-10-18 · publication

The measurable-volume identity and three-dimensional fork bound are distinct from the earlier graph-cancellation results.

Read this published revision