2405.20563
LIMIT SETS, INTERNAL CHAIN TRANSITIVITY AND ORBITAL SHADOWING OF TREE-SHIFTS DEFINED ON MARKOV-CAYLEY TREES
Jung-Chao Ban, Nai-Zhu Huang, Guan-Yu Lai
correctmedium confidence
- Category
- Not specified
- Journal tier
- Strong Field
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper’s Theorem 1.12 states that a tree-shift on a Markov-Cayley tree is TSFT if and only if it has the (projected) shadowing property, with precise definitions given in Definition 1.11 and the theorem statement itself . The forward implication constructs t|g = O(g)|ε and shows d(σg(t), O(g)) < ε (see the argument around equation (3.1)) . The reverse implication is proved contrapositively by building a δ-PPO that cannot be 1-shadowed when T is not TSFT (see (3.2)–(3.8)) . The candidate solution reproduces the forward direction essentially in the same spirit (defining t from root labels of O and using δ < 1/2 to propagate equality) and provides a different, constructive reverse direction via an R-language/gluing argument from a fixed ε0 = 1/2; this also correctly yields finite type. Hence both are correct, with substantially similar forward directions and a different, valid reverse proof.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} strong field \textbf{Justification:} The equivalence between shadowing and finite type is extended from d-trees to Markov–Cayley trees with careful handling of follower-set types. The proofs are correct and thorough. A minor enhancement would be to note that in the TSFT ⇒ shadowing direction one may simply take δ < 1/2 and obtain exact tracing, which streamlines the exposition without changing the result (see the construction around equation (3.1) and the formal statement of Theorem 1.12). This would help readers appreciate the robustness of the forward implication without tracking an auxiliary depth parameter s.