T-226: Couzo's 204 of #670, below Polkovskyi's T-186, since superseded by his own #675 and #678

V0 C0 Upper bound recorded superseded by T-225

2026-10-17 published · Couzo after Polkovskyi, Daniel, Levy · n=204

One complete rational source certificate of issue #670 reports a finite upper-bound improvement at the exact side it states: s(204)≤45044217780850246618141/3041751595240000000000, below T-186, the case's house best packing when it was reported. Complete native feasibility outcomes are retained separately; the case's house best packing is unchanged, since Couzo's own later #675 and #678 (T-223) certificates and Daniel's view of #678's packing (T-225) are smaller, and the entry awaits independent review.

The issue states that each bound is strictly smaller than the source's previous published index and a reviewed comparison envelope including deletion and repeated L borders, and the manifest records the author's checker receipts with the source's exact checker verify_bound_certificate.py (Daniel's MIT verifier, modified by Couzo with Codex), pinned here by digest and not run. Those statements are the author's; no source program ran here.

Credit Couzo (https://github.com/franciscouzo/square-packing), whose per-count JSON credits the 204 seed to Polkovskyi (Mishapolk), search job 105412 (hop). The issue keeps every seed, construction and certificate credit in the source's manifest.

Significance, composition and next rung
Significance
A finite construction side at 204, 1.88e-5 below T-186, Polkovskyi's refinement that held the case when it was reported, and since superseded by Couzo's own #675 (5.05e-8 lower) and #678 (T-223); a step in his 204 sequence that moves no theorem, S2 as T-198 is. No lower bound or optimum.
Next rung
Independently review the retained replay (think-0nse). The entry is superseded on entry at 204: Couzo's own #675 and #678 (T-223) and Daniel's view of #678's packing (T-225) are smaller, and the case holds T-225. The 72 rows beyond the corpus are the source's dated beyond-horizon rows since 22 October 2026, recorded in report order by the backlog ledger (upper-bounds-backlog-20261022).
Unfinished confirmations
C3 (think-0nse): Review the retained two-route replay of #670's 204 certificate and enter it as confirming evidence, with sharp controls at 1e-30. Not priced.
Novelty
previously-published Present in an identified source

The case

Case record

n=204

14.2914.809
141516
14.28315.283
nn+1

Proven

14.29311≤s(204)≤14.808643

  • exact

Citation record n-204

lowerKarakuş 2026, arXiv corrects Nagamochi 2005 (confirmed T-083)

upperCouzo & Daniel, GitHub (confirmed T-225)

Open

  • optimality

The case record

LowerUpper
Gap0.51552861…

Results on the case

15 results in the register on n=204, oldest first, each with what it established and how it stands now.

  1. 2005 published T-007

    s(n)≥min(⌈n⌉,n−2⌊n⌋+1+1) for 4≤n≤324

    V0 C1 Lower bound incomplete on this case, superseded by T-083 and T-180 (reported)

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-09-04 published T-085

    Nagamochi 2005, Lemma 1 is false for every container with a>3 and b>2

    V3 C3 Correction confirmed

    Karakuş; Vlasenko · Karakuş 2026 · chelokot Nagamochi counterexample 2026 · packet · register

  3. 2026-09-29 published T-083

    s(n)≥1/2+n−⌊n⌋+1/4 for every nonsquare 8≤n≤324

    V3 C3 Lower bound confirmed

    Karakuş · Karakuş 2026 · source · register

  4. 2026-10-05 published T-101

    Exact certificates of 77 catalogue packings: s(n) ≤ S', 1.2e-16 to 9.8e-15 above each side

    V3 C3 Upper bound confirmed on this case, superseded by T-225

    Daniel after Couzo, de Winter, Ellsworth, Levy · evand exact optima 2026-10-05 · packet · register

  5. 2026-10-12 established T-155

    Exact regularized sides at 59 counts, 5.4e-20 to 9.9e-15 below the ceilings they replace

    V3 C3 Upper bound confirmed on this case, superseded by T-225

    Levy after Daniel · register

  6. 2026-10-12 published T-162

    New packings of 129, 204 and 303 squares, a cut-out and two compositions, each certified exactly

    V3 C3 Upper bound confirmed superseded by T-225

    Ostashev after Nakajima, Chaoweeraprasit, Daniel, Xu, Levy · Ostashev compositions 2026-10-12 · packet · register

  7. 2026-10-13 published T-174

    Tighter certificates at 68 counts from PingYou Ltd, of others' packings and its own

    V3 C3 Upper bound confirmed on this case, superseded by T-225

    PingYou Ltd after Friedman, Ellsworth, Daniel, Xu, Barnett, Couzo, Ostashev, Chaoweeraprasit, Gupta, Fang, Polkovskyi, Levy · PingYou PR 574 certificates 2026-10-13 · packet · register

  8. 2026-10-13 published T-180

    Closed-form lower bound s(N)≥a(N) for every non-square N≥49, reported

    V0 C1 Lower bound reviewed

    Hosono · wand125 closed form 2026-10-14 · packet · packet · register

  9. 2026-10-14 published T-186

    Exact certificates at twelve counts from Polkovskyi, tightening the smallest reported there

    V3 C3 Upper bound confirmed on this case, superseded by T-225

    Polkovskyi after Ostashev, Couzo, PingYou Ltd, Levy · Mishapolk KKT refinements 2026-10-14 · packet · register

  10. 2026-10-16 published T-193

    Exact algebraic sides at sixteen counts from Daniel, of packings the record credits

    V3 C3 Upper bound confirmed on this case, superseded by T-225

    Daniel after Xu, Chaoweeraprasit, Ostashev, Couzo, PingYou Ltd, Gupta, Polkovskyi, Levy · Daniel exact current records 2026-10-16 · packet · register

  11. 2026-10-17 published T-226 this result

    Couzo's 204 of #670, below Polkovskyi's T-186, since superseded by his own #675 and #678

    V0 C0 Upper bound recorded superseded by T-225

    Couzo after Polkovskyi, Daniel, Levy · Couzo issue 670 2026-10-17 · packet · packet · register

  12. 2026-10-18 published T-223

    Couzo's smaller packings at 204 and 260, the two in the corpus of issue 678's 85 bounds

    V3 C3 Upper bound confirmed superseded by T-225

    Couzo after de Winter, Polkovskyi, Daniel, Fang, PingYou Ltd, Levy · Couzo issue 678 2026-10-18 · packet · register

  13. 2026-10-18 published T-228

    Couzo's 204 of #675, below his #670, since superseded by his #678

    V0 C0 Upper bound recorded superseded by T-225

    Couzo after Polkovskyi, Daniel, Levy · Couzo issue 675 2026-10-18 · packet · packet · register

  14. 2026-10-20 published T-225

    Daniel's solved, regularized views at 204, 227, 229 and 260, each the smallest side reported there

    V3 C3 Upper bound confirmed

    Daniel after Couzo, de Winter, Polkovskyi, Levy · Daniel regularized lists 2026-10-20 · packet · register

  15. 2026-10-22 published T-229

    Polkovskyi's re-solves of the house packings at 105 and 204, below T-174 and T-225

    V0 C0 Upper bound recorded

    Polkovskyi after Couzo, Muglich, Daniel, Xu, PingYou Ltd, Levy · Mishapolk issue 719 2026-10-22 · packet · register