2504.07267
Fans, phans and pans
Iztok Banič, Goran Erceg, Ivan Jelić, Judy Kennedy, Van Nall
correcthigh confidence
- Category
- Not specified
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper proves that in a 1‑dimensional hereditarily unicoherent continuum X which is the union of arcs whose pairwise intersections are exactly {v}, the only ramification point is v (Lemma 3.2), and then asserts X is a fan (Theorem 3.3) . While the paper does not explicitly spell out why X is arcwise connected, this follows immediately from the union‑of‑legs structure. The candidate solution supplies this missing step and also shows v is indeed a ramification point when |L|≥3. The candidate’s proof of uniqueness of ramification points is sound in idea but contains a minor slip (“removing x from an arc leaves exactly two components,” which fails when x is an endpoint); this is easily patched. Hence both are substantively correct, with different proof details.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} specialist/solid \textbf{Justification:} The main theorem under review (the converse under hereditary unicoherence) is correct and well-motivated. The proof of Lemma 3.2 is concise and effective, and Theorem 3.3 follows once one explicitly notes the immediate arcwise connectedness of the union-of-legs structure. Clarifying this step and harmonizing the definition of 'fan' would polish the presentation.