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2101.10406

PERIODIC ORBITS IN RÖSSLER SYSTEM

Anna Gierzkiewicz, Piotr Zgliczyński

correctmedium confidence
Category
math.DS
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:55 AM

Audit review

The paper rigorously proves: (i) for a=5.25, b=0.2 the Poincaré map has n-periodic points for every n via verified horizontal covering relations N0⇒N1, N1⇒N1, N1⇒N0 (plus a validated 3-cycle), yielding all periods; (ii) for a=4.7, b=0.2 there is an explicit forward-invariant parallelogram A with P(A)⊂A, coverings that force all periods except {2,3,4} inside A, 2- and 4-cycles certified by interval Newton, and a proof that no fundamental 3-cycle exists in A by showing the unique zero of P^3−Id in A is actually a fixed point of P. The candidate solution misstates key proof details: it (a) claims a full topological horseshoe (four coverings) for a=5.25 when the paper verifies a different three-relation scheme; (b) suggests coverings alone yield all periods n≠3 for a=4.7, overlooking that 2 and 4 are obtained by interval Newton; and (c) asserts ‘no zero of P^3−Id in A,’ contradicting the paper’s actual ‘unique zero which is also a fixed point of P’ argument. Hence the paper is correct, but the model’s proof description is incorrect in important respects.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The article provides rigorous, computer-assisted existence proofs of abundant periodic orbits for the Rössler system at two parameter values. The methodology—horizontal covering relations plus validated numerics—is sound and clearly situated within established CAPD practice. The main results (all periods for a=5.25; all except 3 inside a forward-invariant set for a=4.7, with explicit exclusion of fundamental period 3) are well supported. Minor clarifications of the certified covering graphs, and expanded reproducibility details (affine changes; grid parameters), would further enhance clarity.