Record compositions of alternating permutations and noncommutative symmetric functions

Evan Chen, Ken Ono, Michal Mogielnicki

For each composition α=(α₁,…,α_k) of n, the number of alternating permutations of 2n with record composition α is ∏_j binom(2s_j−1,2α_j−1)E_(2α_j−1), where s_j=α₁+…+α_j and E_m is an Euler number. The paper also realizes these counts in a noncommutative symmetric-function lift.

Sources for this record

What was already known

Amdeberhan, Shareshian and Stanley established the coarser record-partition count and asked for a composition refinement with an algebraic interpretation.

AI involvement AI-autonomous

AxiomProver received the theorem statements without a solution and generated the proofs and Lean formalizations. Chen, Mogielnicki and Ono wrote the explanatory paper.

The source states that AxiomProver received only the three theorem statements and generated the mathematical proofs and formalization without a supplied solution.

Importance Notable

Resolves the record-composition refinement and supplies an algebraic description.

Limitations

The authors report complete Lean proofs and provide a separate human exposition. A separate complete human check of each generated proof is not documented.

Technical verification Formal (Lean 4.31.0)

The authors report complete Lean 4.31.0 proofs. The released problem statement names the exact record-composition product and noncommutative lift; the released solution contains the corresponding proofs without sorry. Human exposition is not counted as a separate completed proof check.

Formal checking

Complete Lean formalization in problem.lean and solution.lean

Checker
Lean 4.31.0 type checker, as reported by AxiomMath
Scope
The record-composition product formula and noncommutative symmetric-function lift in Theorems 1.1–1.3
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 authors give a direct bijection via record blocks, derive the product formula and explain its noncommutative symmetric-function lift.

Correction and publication history