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2405.08940

Dynamical systems and complex networks: A Koopman operator perspective

Stefan Klus, Nataša Djurdjevac Conrad

incompletemedium confidence
Category
math.DS
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:56 AM

Audit review

The uploaded paper is a perspective/review that defines the transfer operators and notes when they are self-adjoint, but it does not state or prove the trace bounds on joint metastability the model solves. The model’s proof is essentially correct once a crucial missing hypothesis is added: T must be compact and self-adjoint (e.g., reversible dynamics with µ equal to the invariant density), which the paper explains is the case under detailed balance. Without explicitly assuming self-adjointness, the model’s use of the spectral theorem and Ky Fan’s principle is not justified.

Referee report (LaTeX)

\textbf{Recommendation:} major revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The paper supplies the relevant background (operator definitions, self-adjointness under reversibility, Ulam's indicator subspace) but does not state the metastability trace bounds under review. The model's proof achieves these bounds once the key hypothesis (compact self-adjoint T, e.g., reversible with µ=π) is made explicit; as written, that hypothesis is omitted, so the spectral expansion and Ky Fan step are not fully justified.