T-224: Daniel's smaller n270 packing, another arrangement found from Chaoweeraprasit's, certified exactly

V3 C3 Upper bound confirmed

2026-10-20 published · Daniel after Chaoweeraprasit, Levy · n=270

One complete rational source certificate reports a finite upper-bound improvement at the exact side it states: s(270)≤16.928162252196750114897964982713.

The certificate and its duplicate-square and outside-container controls were decided here on 21 October 2026 by both maintained exact routes, and the frozen comparison rebuilt; no route here is the source's code, so the replay is independently re-implemented. The 21 October review found no blocking defect.

Issue 703 reports a packing found by Daniel's basin explorer in a near-record sweep over stored non-record descendants of Chaoweeraprasit's (itsnaka's) #500 packing (T-151), the register's s(270) packing, which PingYou Ltd refined in PR #574 (T-174); it asks that #500's packing be credited as the ultimate start, and calls this a new packing, a different local minimum from the register's. Measured here pose by pose, the packing is another arrangement of the design that the case's earlier house best packing (T-174) holds, not a refinement of it, found from #500's packing as the source describes.

The author reports that his two exact checkers, verify_cert.py (separating axes) and verify_cert2.py (polygon intersection), accept the certificate, and a KKT local minimum strict modulo 23 exact flat motions and not isolated, with 263 corner-corner contacts, no corner-corner MILP descent, 1 rattler and 67 tilted squares; those are numerical evidence at 80 digits, not proofs. The source's credits say the work was done with Claude (Anthropic) under Daniel's direction.

Significance, composition and next rung
Significance
Another arrangement of the design at 270, 3.47e-05 below the case and every report there, to a new KKT point with 15 squares moved beyond a tenth, two fewer tilted squares and no tilt angle shared; a smaller margin than #664's 271 (4.46e-05, three squares, S3) and #689's 308 (1.12e-03, S3), with as many squares beyond a tenth as the 308 (15), and well above T-188's 9.29e-06 (S2); no lower bound or optimum.
Next rung
None for the bound. V4 and C4 need a second accepted adversarial review by a distinct reviewer and a retained human oversight record; one AI review, of 21 October, is retained.
Regularized drawings
n = 270: a regularization of T-224’s packing by Levy (Daniel's search/regularize (MIT), evand/square-packing@675a5ea, conservative, coincide, through devtools.regularize_evand; unmodified; at its own side; 1 free square straightened; identity: measured here; nearest centres one to one; 24 squares moved, at most 0.13034; turns up to 0.217543°).
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 n270 sweep 2026-10-20]

n=270

16.4416.928
161718
16.43217.432
nn+1

Proven

16.44521≤s(270)≤16.928163

  • exact

Citation record n-270

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

upperDaniel 2026, GitHub (confirmed T-224)

Open

  • optimality

The case record

LowerUpper
Gap0.48294353…

Results on the case

15 results in the register on n=270, 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-224

    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-224

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

  6. 2026-10-07 published T-119

    Three exact feasible upper bounds at n=266,270,272 from new source arrangements

    V3 C3 Upper bound confirmed on this case, superseded by T-224

    Daniel after Levy, Ellsworth, Couzo, Stead · Daniel new arrangements 2026-10-07 · packet · register

  7. 2026-10-08 published T-130

    Five follow-up rational refinements from Couzo

    V3 C3 Upper bound confirmed superseded by T-224

    Couzo after Xu, Daniel, Ellsworth, Levy · Couzo follow-up refinements 2026-10-08 · packet · register

  8. 2026-10-09 published T-134

    Six exact rational certificates from Couzo

    V3 C3 Upper bound confirmed on this case, superseded by T-224

    Couzo after Polkovskyi, Chaoweeraprasit, Gupta, Xu, Daniel, Ellsworth, Levy · Couzo exact certificates 2026-10-09 · 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-224

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

  10. 2026-10-09 published T-138

    Exact witnesses at Mishapolk's printed ceilings, the smallest known at 103 and 258 when registered

    V3 C3 Upper bound confirmed superseded by T-224

    Polkovskyi after Stenlund, Friedman, Ellsworth, Chaoweeraprasit, Couzo, Xu, Levy · Mishapolk decimal poses 2026-10-09 · packet · register

  11. 2026-10-10 published T-140

    Six more exact rational certificates from Couzo

    V3 C3 Upper bound confirmed superseded by T-224

    Couzo after Chaoweeraprasit, Polkovskyi, Xu, Daniel, Ellsworth, Levy · Couzo certificates 2026-10-10 · packet · register

  12. 2026-10-11 published T-151

    Nine exact rational packings from SQUISH's fourth request

    V3 C3 Upper bound confirmed superseded by T-224

    Chaoweeraprasit after Couzo, Gupta, Ellsworth, Friedman, Levy · SQUISH fourth request 2026-10-11 · packet · register

  13. 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-224

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

  14. 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

  15. 2026-10-20 published T-224 this result

    Daniel's smaller n270 packing, another arrangement found from Chaoweeraprasit's, certified exactly

    V3 C3 Upper bound confirmed

    Daniel after Chaoweeraprasit, Levy · Daniel n270 sweep 2026-10-20 · packet · register