slug: filimonova-puzynina-2026-rank-one-iteration-bound bibkey: filimonovapuzynina2026abelianperiodicity doi: null url: https://arxiv.org/abs/2605.30306v1 triage: theorem motivation_gids:

• D5/S1/Words/RankOneMorphismIterationBound

Filimonova–Puzynina’s rank-one iteration-bound question

Problem

Filimonova and Puzynina ask in Section 4 of On abelian periodicity of purely morphic words (arXiv:2605.30306v1) whether the iteration variable in their primitive binary rank-one criterion has an upper bound making the criterion algorithmic.

The source’s fixed word is allowed an arbitrary finite preperiod. The target is the complete nonerasing, prolongable, primitive, rank-one binary domain, with exact Parikh equality in the cyclic block witness.

Motivation

The question asks for an effective version of the source criterion. A total bound from the two actual image lengths also gives a finite decision procedure for eventual abelian periodicity.

Gap

The source states the criterion but leaves the iteration bound open. The preregistration and bounded prior-art screen are recorded in issue #13429.

Route

The proof extracts the coprime rank-one parameters, presents the actual iterates through a finite uniform expansion, and encodes cyclic witnesses as constant-output subset paths. There are at most 2^(|f(0)|+|f(1)|) subset states, so any accepted path can be shortened to that bound. Height rays and recurrent source residues establish the reverse direction for arbitrary preperiods and retain the original cyclic witness.

Falsifier

A morphism satisfying the complete source hypotheses with an ultimately abelian-periodic fixed word but with no witness at any 1 ≤ K ≤ 2^(|f(0)|+|f(1)|) would refute the result. A witness using a proxy fixed word, pure periodicity, a fixed-K hypothesis, or a frequency-only equivalence would not address this problem.

Evidence

D5/S1/Words/RankOneMorphismIterationBound.effective_iteration_bound proves the full bounded equivalence. finiteChecker_uap proves correctness of the executable finite-image checker for the same domain. The source modules and their exact-type importing clients compile under the pinned Lean/Mathlib environment; the importing client’s axiom closure is only propext, Classical.choice, and Quot.sound.

The source module and its proof dependency closure are registered in the Frozen state. The canonical Scribe description binds the Proved resolution to effective_iteration_bound. Issue #13429 records the preregistration and the complete kernel-checked evidence; issue #14423 tracks completion of the missing publication records.

Triage

theorem; the formal result settles the registered iteration-bound question on the complete source domain.

ASSUMED-UNVERIFIED

The literature screen is bounded by the searches recorded in issue #13429. It does not establish worldwide absence or priority.