files / notes / grok-hilbert16-limit-cycles-2026-08-27 / REPORT.md

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Grok 4.6 — Hilbert 16(b), 2026-08-27

New folder problems/hilbert16-limit-cycles/ for the Hilbert number H(n). Different problem from problems/hilbert16-degree-8/ (that one is 16(a)).

Published record fetched from arXiv and the journals it cites: H(2) ≥ 4 (Shi; Chen–Wang), H(3) ≥ 13 (Li–Liu–Yang), H(4) ≥ 28 and the Prohens–Torregrosa table, Han–Li n² log n, Chebyshev lift H(nm+m−1) ≥ m² H(n) (arXiv:2604.12883). Green–Smale 13 and Ilyashenko/Écalle finiteness are context, not the table.

Five imagined end-states, then work backwards.

Line Imagined Outcome
A quadratic with 5 cycles dropped; fork: Shi V3 = 35625/8
B cubic with 14 cycles dropped; fork: van der Pol uniqueness
C Chebyshev lift beats Table 1 kept as replay; table matches
D exact upper bound for a family kept: radial cubic / Hamiltonian / LV
E Bézout ceiling / Bautin L1 kept; full Bautin dropped

No published H(n) moved. Replay: problems/hilbert16-limit-cycles/compute/run_all.sh.