2209.05113
NEW SOLVABLE SYSTEM OF 2 FIRST-ORDER NONLINEARLY-COUPLED ORDINARY DIFFERENTIAL EQUATIONS
F. Calogero, F. Payandeh
incompletehigh confidence
- Category
- Not specified
- Journal tier
- Note/Short/Other
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper introduces the system ẋ1 = (x1 + α1 x2)/Q, ẋ2 = (−x2 + α2 x1)/Q with Q = β1 x1^2 + (α1β1 + α2β2) x1 x2 + β2 x2^2, and states a Proposition giving the explicit IVP solution x_n(t) = γ_{n1} sqrt(1 + t/t1) + γ_{n2} sqrt(1 + t/t2) together with closed-form expressions for γ’s, t1, t2, but provides no derivation and explicitly invites the reader to verify the formulas (2)–(3). The candidate solution supplies a detailed and correct verification via a linear-algebraic factorization (J,B) showing that U and V are B-null directions interchanged by J, that Q(x(t)) factorizes as 2(γ1^T B γ2) y1 y2, and that the ODE is matched when 1/t1 and 1/t2 are chosen as in the paper; it also discusses the natural domain/uniqueness restrictions away from Q=0, which the paper does not address beyond a brief remark about square-root branches and possible singularities.
Referee report (LaTeX)
\textbf{Recommendation:} major revisions \textbf{Journal Tier:} note/short/other \textbf{Justification:} This short note presents a compact, elegant family of explicitly solvable 2D nonlinear ODEs with solutions given in closed form. However, the manuscript currently lacks a proof or even a proof sketch for its central Proposition, and it does not articulate the natural hypotheses (e.g., nonvanishing denominators, nondegenerate parameter choices) under which the formulas are valid. Adding a concise derivation and a discussion of degenerate/edge cases would raise the paper to a publishable standard while preserving its brevity.