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2106.08489

Lorenz System State Stability Identification using Neural Networks

Megha Subramanian, Ramakrishna Tipireddy, Samrat Chatterjee

correctmedium confidence
Category
Not specified
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper defines left/right regimes by the per-trajectory mean of x and labels stability via a 5-past/5-future window (a point is stable iff all 10 neighbors are in the same regime) . It then normalizes each Lorenz trajectory feature-wise by subtracting its own mean and dividing by a positive scale (called “standard deviation” in the text, but Eq. (5c) is actually the second central moment), and asserts—empirically via Fig. 13—that normalization does not change the relative positions of stable/unstable points, only the axis ranges . The candidate solution gives a concise proof: per-trajectory standardization is an affine, strictly increasing map that preserves the sign of x−μ and hence preserves regime membership and the window-based stability rule. It also notes the degenerate s=0 case and that normalizing y,z,derivatives is irrelevant since the rule depends only on x. Therefore, the claim is correct; the paper presents it empirically/heuristically, while the model supplies a clean formal proof.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

A clear application paper that defines a sensible labeling rule for Lorenz63 and shows that simple per-trajectory normalization greatly reduces covariate shift, yielding strong gains on mismatched validation data. The key invariance claim (labels unaffected by such normalization) is correct but only argued via figures; adding a short formal proof would strengthen rigor. Minor ambiguities (variance vs. standard deviation in the printed formula, tie/edge handling) should be fixed.