2501.04450
ON THE BASINS OF ATTRACTION OF A ONE-DIMENSIONAL FAMILY OF ROOT FINDING ALGORITHMS: FROM NEWTON TO TRAUB.
Jordi Canela, Vasiliki Evdoridou, Antonio Garijo, Xavier Jarque
correcthigh confidence
- Category
- math.DS
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The uploaded paper proves exactly the statement in the two special cases (quadratic polynomials and unicritical polynomials z^n−β) for all δ∈[0,1], and by the same core arguments used in the candidate solution: (i) local multipliers at roots (Lemma 2.1) ensure attraction (simple roots are superattracting; multiple roots are attracting for a large disk of δ that includes [0,1]) ; (ii) behavior at ∞ and degree considerations (Lemma 2.2) show ∞ is fixed and repelling for δ in [0,1] ; (iii) in the quadratic case, an explicit Möbius conjugacy yields G_δ with formula (14), G_δ is a Blaschke product for real δ, and 1 lies on the common boundary of the immediate basins of 0 and ∞; simple connectivity then holds throughout the hyperbolic component containing δ∈(0,1] (with δ=0 handled by the classical Newton case) ; (iv) in the unicritical case, rotational symmetry and a single finite pole force simple connectivity (Proposition 4.3), and unboundedness follows from the real-axis inequality 1<T(x)<x for x>1, proved via the S_{δ,n}(x) polynomial and Descartes’ rule (Proposition 4.4) . The candidate’s write-up mirrors these steps closely, including the same conjugacy to G_δ, the rotation-symmetry argument, and the real-axis proof of unboundedness. Minor differences are expository (e.g., a direct local expansion at roots versus citing Lemma 2.1), but there is no substantive disagreement with the paper.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} specialist/solid \textbf{Justification:} The manuscript proves sharp results in two natural regimes of the Traub family using clean, transparent arguments that align with standard complex dynamics. The presentation is largely clear, with only minor spots where auxiliary computations (e.g., for S\_{δ,n}) could be centralized for readability. The conclusions are well-supported and of interest to researchers studying iterative root-finding dynamics and the topology of basins.