2410.05520
What is the graph of a dynamical system?
Chirag Adwani, Roberto De Leo, James A. Yorke
incompletemedium confidence
- Category
- Not specified
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper’s Theorem 1 states that if the global attractor G is connected, then the chain graph is connected, and gives a four-case proof in Section 7.3. However, two key steps are left unjustified: (i) in Case M the argument jumps from the existence of points in C arbitrarily close to N to the existence of a weak edge from some node of M to some node of N, without constructing the required ε-chains or citing a lemma that would imply this (see “Since G is connected … Hence, there is a weak edge …” in the proof of Theorem 1) ; and (ii) in the Remaining Case the sets M+ and N+ are asserted to be closed without providing the needed upper semicontinuity statements for α- and ω-limit sets (also in ). By contrast, the candidate solution supplies a complete, stand-alone proof: it gives an explicit ε-chain lemma showing how an ω-limit set intersecting both node blocks creates a directed edge, proves upper semicontinuity of x↦ω(x) on compact G, and then uses these to produce a separation of G by disjoint open sets—contradicting connectedness. The model also cleanly reduces continuous time to the time-1 map, in line with the paper’s intent around Proposition 4, whose full details are likewise deferred in the paper . Hence the theorem is correct, but the paper’s proof is incomplete, whereas the model’s proof is complete and correct.
Referee report (LaTeX)
\textbf{Recommendation:} major revisions \textbf{Journal Tier:} specialist/solid \textbf{Justification:} The paper introduces a useful, broadly applicable notion of chain graph and illustrates it with compelling examples across discrete, ODE, and PDE settings. The main connectedness theorem is natural and impactful, but its proof as written omits crucial steps: deriving an across-edge in Case M from proximity alone, and establishing the closedness of the sets used in the Remaining Case. Some details in the time-T map reduction are also deferred. With these issues addressed, the manuscript would be solid and publishable.