T-172: A packing of 154 squares from Couzo, continuing Daniel's arrangement

V3 C3 Upper bound confirmed superseded by T-222

2026-10-12 published · Couzo after Daniel, Ostashev, Fang, Ellsworth, Levy · n=154

One complete rational source certificate reports a finite upper-bound improvement at the exact side it states: s(154)≤12.922499814642397493692375652931.

All 21 retained jobs of the packet, its seven certificates with their duplicate-square and outside-container controls, were decided again here on 14 October 2026 by both maintained exact routes and equal their retained rows. A third exact route, half-extent containment and exact intersection area, decided the certificate with six controls each and held the retained file to its upstream bytes, fetched at the pin. No route here is the source's code; the author's runs of this repository's sqpack verifier are his and decide nothing here, so the replay is independently re-implemented. The 14 October review found no blocking defect.

Issue 570 names the certificate by its digest at a revision of franciscouzo/square-packing that GitHub no longer serves; the same bytes are certificates/n154.cert at the revision issue 583 pins, where the couzo-issue583-2026-10-13 packet retains them. The issue also reports s(379)≤19.953542593650, by a certificate in no reachable commit of the source, which is not retained and has no row here.

The author reports that the certificate passes this repository's sqpack verify.py and Daniel's verify_cert.py, at the revisions the issue names, in exact rational arithmetic; that statement is the author's. Both maintained exact routes accept it here and refuse its two controls.

Credit Couzo (https://github.com/franciscouzo/square-packing), continuing Daniel's arrangement of issue 552 (T-160) through the author's browser refinement, native basin hopping and exact finishing, with Daniel's exact contact solver. The author states that OpenAI Codex assisted the search and verification and that he directed the work.

Measured pose by pose by that review, it refines Daniel's packing (T-160) under a quarter turn, every square paired and none moved beyond 0.04. At 154 the same author's issue 586 (T-182) is smaller and has held the case since 15 October 2026.

Significance, composition and next rung
Significance
A refinement of Daniel's packing (T-160) to a new side 6.66e-05 below it, as T-152 and T-128 are; no lower bound or optimum.
Next rung
V4 and C4 need a second accepted adversarial review by a distinct reviewer and a retained human oversight record; one AI review, of 14 October, is retained.
Novelty
previously-published Present in an identified source

The case

Case record
Regularized by the Squares Project with Daniel's regularizer (evand/square-packing, MIT)
As published
The packing as published, Daniel 2026 [Daniel n154 sweep 2026-10-20]

n=154

12.4212.921
121314
12.41013.410
nn+1

Proven

12.42686≤s(154)≤12.921101

  • exact

Citation record n-154

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

upperDaniel & Couzo, GitHub (confirmed T-222)

Open

  • optimality

The case record

LowerUpper
Gap0.49424049…

Results on the case

15 results in the register on n=154, 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. 2026-09-27 published T-056

    Smaller packings for 49 counts from n=68 to 307, each certified two independent ways

    V3 C3 Upper bound confirmed superseded by T-222

    Couzo · franciscouzo square-packing 2026-09-27 · packet · register

  4. 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

  5. 2026-10-05 published T-098

    Exact optima of 48 known-best packings: s(n) ≤ S', 3.5e-13 to 5.0e-11 below each printed side

    V3 C3 Upper bound confirmed on this case, superseded by T-222

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

  6. 2026-10-07 published T-113

    s(n)≤Sn at ten counts, n=108 to 303, from new SQUISH rational packings

    V3 C3 Upper bound confirmed superseded by T-222

    Chaoweeraprasit after Ellsworth · SQUISH ten packings 2026-10-07 · packet · register

  7. 2026-10-07 published T-115

    s(n)≤Sn at twelve counts, from the SQUISH update’s new and smaller rational packings

    V3 C3 Upper bound confirmed superseded by T-222

    Chaoweeraprasit after Couzo and Ellsworth · SQUISH update 2026-10-07 · packet · register

  8. 2026-10-08 published T-127

    Fourteen rational refinements, seventeen complete source cases

    V3 C3 Upper bound confirmed on this case, superseded by T-222

    Gupta after Chaoweeraprasit, Daniel · Gupta rational refinements 2026-10-08 · packet · register

  9. 2026-10-09 published T-136

    Seventeen exact rational packings from SQUISH's third request

    V3 C3 Upper bound confirmed on this case, superseded by T-222

    Chaoweeraprasit after Couzo, Xu, Göbel, Schadt, Ellsworth, Hajba, Levy · SQUISH third request 2026-10-09 · packet · register

  10. 2026-10-12 published T-160

    A smaller packing of 154 squares from Daniel's size-chaining explorer, certified exactly

    V3 C3 Upper bound confirmed superseded by T-222

    Daniel after Couzo, Levy · Daniel n154 2026-10-12 · packet · register

  11. 2026-10-12 published T-172 this result

    A packing of 154 squares from Couzo, continuing Daniel's arrangement

    V3 C3 Upper bound confirmed superseded by T-222

    Couzo after Daniel, Ostashev, Fang, Ellsworth, Levy · Couzo issue-583 certificates 2026-10-13 · packet · register

  12. 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

  13. 2026-10-13 published T-182

    Exact rational certificates at 154, 211 and 241 from Couzo

    V3 C3 Upper bound confirmed on this case, superseded by T-222

    Couzo after Daniel, Ostashev, BuddenPing, Fang, Ellsworth, Levy · Couzo certificates 2026-10-13 · packet · register

  14. 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-222

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

  15. 2026-10-20 published T-222

    Daniel's smaller n154 packing, continuing Couzo's #586 arrangement, certified exactly

    V3 C3 Upper bound confirmed

    Daniel after Couzo, Ostashev, Levy · Daniel n154 sweep 2026-10-20 · packet · packet · register