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2406.15705

ON THE MINIMAL NUMBER OF CLOSED GEODESICS ON POSITIVELY CURVED FINSLER SPHERES

Huagui Duan, Dong Xie

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

Audit review

The paper proves that every Finsler metric on S^n (n ≥ 4) with reversibility λ and flag curvature K satisfying ((2n−3)/(n−1))^2(λ/(λ+1))^2 < K ≤ 1 and λ < (n−1)/(n−2) carries at least n prime closed geodesics (Theorem 1.1). The argument uses: (i) Rademacher’s length and index bounds to obtain i(cm) ≥ floor(((2n−3)m)/(n−1))(n−1) and mean index î(c) > 2n−3 (Lemma 4.1), (ii) the enhanced common index jump theorem to place iterates symmetrically around 2N (equalities (4.6)–(4.9)), (iii) an S^1–equivariant Morse/Fadell–Rabinowitz construction to get n−2 primes in a first window and one more elliptic prime c_{j0} with a critical module concentrated at degree 2N+n−1 (Lemma 4.3), and (iv) a second disjoint window to derive a contradiction unless an additional prime exists, giving at least n total. These steps and degree placements are set out explicitly in the paper’s outline and proofs (see the statement of (1.2) and Theorem 1.1, Lemma 4.1, (4.6)–(4.9), Claim 1 (4.42), and Step 2’s contradiction) . The candidate’s solution follows the same blueprint: the same pinching drives the same index lower bounds; ECIJT supplies the same symmetric index placement; S^1–equivariant Morse/FR index is used to populate degrees; and an elliptic/non-hyperbolicity input plus a second window yields the nth geodesic. The two main discrepancies are that the candidate (a) claims n−1 geodesics already arise in a single “left half-window,” whereas the paper first produces n−2 in G1 and then one more via the elliptic c_{j0} outside that window, and (b) locates the extra elliptic contribution “at the center 2N,” while the paper concentrates it at degree 2N+n−1; nonetheless, these are refinements of placement rather than essential changes of method. With these clarifications, the candidate’s proof aligns with the paper’s and reaches the same conclusion under the paper’s hypotheses .

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

This work advances lower bounds for closed geodesics on positively curved Finsler spheres under explicit pinching and reversibility constraints, combining modern index iteration with ECIJT and S\^1–equivariant Morse/FR index techniques. The two-window argument is persuasive and well integrated with the topological input. A few places where degree bookkeeping and the role of constants are implicit could be made more explicit, but the contribution is solid and technically competent.