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2408.01560

Stochastic bifurcation of a three-dimensional stochastic Kolmogorov system

Dongmei Xiao, Deng Zhang, Chenwan Zhou

correctmedium confidence
Category
Not specified
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves a stochastic decomposition: x(t) = g(t) Ψ(∫ g^2, x/g0), where g solves a one-dimensional stochastic logistic equation (3.7). This yields: (i) a scalar radial factor g (hence Z=g^2) with threshold σ^2=2α for extinction vs persistence, and (ii) deterministic angular dynamics via a time change. From this they classify all ergodic stationary measures (rays and invariant cones) and Lyapunov exponents at δO, exactly matching the candidate’s reduction to a logistic diffusion for Z and a time-changed copy of (1.3). The paper’s Theorem 1.1 and Theorem 1.3 coincide with the model’s items (1)–(3a)–(3c), and Lemma 6.1 gives λi(δO)=α−σ^2/2 as in the model. The two arguments are essentially the same structure (radial logistic + deterministic direction via time-change), with the paper using an explicit decomposition formula and strong Feller/irreducibility on cones, and the model using an Ito/log-ratio and generator-splitting viewpoint. No substantive conflict detected. Citations: decomposition and logistic eq (3.7) with ug(ω) and threshold at 2α ; main classification Theorem 1.1 (rays vs cones) and pull-back Ω-limits Theorem 4.1/1.3 ; ray/cone stationary measures and uniqueness on cones (Props. 5.1, 5.3, 5.4) ; Lyapunov exponents Lemma 6.1 .

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The manuscript gives a comprehensive and technically sound analysis of a 3D stochastic Kolmogorov system with common multiplicative noise, centered on a clean decomposition into a scalar logistic factor and a time-changed deterministic flow. The bifurcation picture (unique ergodicity vs. multiple ray/cone-supported measures) and the link to Lyapunov-exponent sign are clearly established. Minor improvements could increase accessibility (e.g., explicit \$Z\$-equation, a schematic of the skew-product).