Spectral Gap for the Binary Fixed-Margin Swap Chain

Weibo Fu, Qian Qin, Guanyang Wang

For every feasible set of row and column margins on an m×n binary matrix, with m,n≥2, the lazy 2×2 swap chain has spectral gap at least 1/[binom(m,2)binom(n,2)].

Sources for this record

What was already known

Rapid mixing was known for restricted margin classes; the unrestricted fixed-margin bipartite case of the Kannan–Tetali–Vempala conjecture remained open.

AI involvement AI-led

The authors credit ChatGPT 5.5 Pro with the comparison strategy, three-row reduction, harmonic decomposition and initial proofs. They posed and directed the problem, evaluated the arguments and rewrote the paper.

The model is credited with the full mathematical strategy and initial lemmas, while the author directed and rewrote the work.

Importance Major

Gives a uniform polynomial mixing bound for all feasible fixed-margin binary matrices.

Limitations

The result is for bipartite binary matrices, not arbitrary undirected degree-sequence graphs. The Lean repository identifies the theorem and build instructions but provides no independent build log.

Technical verification Formal (Lean 4)

The paper reports full Lean formalization of its main theorem, and the repository identifies the paper-facing spectral-gap theorem and build instructions. The reviewed repository README describes an intended sorry-free build but provides no independent build log; Formal records the source-reported formalization, without claiming AIProofWatch reproduced it.

Formal checking

The paper and repository report a Lean proof of the fixed-margin spectral-gap bound.

Checker
Lean formalization maintained by the paper author
Scope
Paper-facing fixed-margin lazy swap-chain spectral-gap bound
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 human author evaluated and rewrote the proof, and the paper explains the heat-bath comparison, three-row reduction and harmonic decomposition.

Correction and publication history