T-230: Daniel's smaller n303 packing, started from Ostashev's packing, certified exactly

V3 C3 Upper bound confirmed superseded by T-240

2026-10-22 published · Daniel after Ostashev, Levy · n=303

One complete rational source certificate reports a finite upper-bound improvement at the exact side it states: s(303)≤447744305431858194305431410441/25000000000000000000000000000 = 17.90977221727432777221725641764, 1.86e-4 below T-186, the case's house best packing when it was reported.

The certificate and its duplicate-square and outside-container controls were decided here on 22 October 2026 by both maintained exact routes, and the frozen comparison rebuilt. No route here is the source's code, but both read it through an adapter that carries two of the source checkers' expressions transcribed, so the replay shares those components with the producer (RF-1). The 22 October review decided the certificate again on a clean-room checker of its own and found no blocking defect, so the bound is confirmed, independently re-implemented.

Issue 728 reports a packing found by Daniel's search from Ostashev's packing (#562, T-162, the house's packing through T-186): a basin explorer, near-record sweeps and crossovers, and a final band flip, which reflects one of the packing's two tilted bands along its wall. Measured here pose by pose, it is another arrangement than the house's, not a refinement of it. The issue states a dilation certificate of a binary64 packing, scaled by 1 + 10^-12, and leaves local optimality unresolved: the author's exact solver finds the packing not first-order jammed, and a further descent of about 4.8e-7 is predicted and not realised. The source's credits say the work was done with Claude (Anthropic) under Daniel's direction.

Significance, composition and next rung
Significance
A new arrangement at 303, 1.86e-04 below the case and every report there, found from Ostashev's packing, as T-197 at 155 (1.64e-04) is; 64 squares lie beyond a tenth of the house's packing and 24 tilts are reversed, against T-197's 29 and the 15 of T-224 and T-221 beyond a tenth, 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 22 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, in its source’s pose, Vladislav Lavrentev 2026 [Couzo issue 763 2026-10-23]

n=303

17.4117.907
171819
17.40718.407
nn+1

Proven

17.41892≤s(303)≤17.906979

  • exact

Citation record n-303

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

upperLavrentev & Couzo, GitHub (confirmed T-240)

Open

  • optimality

The case record

LowerUpper
Gap0.48805391…

Results on the case

18 results in the register on n=303, 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-240

    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. 2026-10-03 published T-092

    Smaller packings again at seven counts from n=208 to 306, each certified two independent ways

    V3 C3 Upper bound confirmed superseded by T-240

    Couzo · franciscouzo square-packing 2026-10-03 · packet · register

  6. 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-240

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

  7. 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-240

    Chaoweeraprasit after Ellsworth · SQUISH ten packings 2026-10-07 · 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-240

    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 superseded by T-240

    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-240

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

  11. 2026-10-10 published T-146

    Exact rational certificates at fifteen counts from Daniel's regularized record lists

    V3 C3 Upper bound confirmed on this case, superseded by T-240

    Daniel after Xu, Chaoweeraprasit, Polkovskyi, Levy · Daniel regularized lists 2026-10-10 · packet · register

  12. 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-240

    Ostashev after Nakajima, Chaoweeraprasit, Daniel, Xu, Levy · Ostashev compositions 2026-10-12 · 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-240

    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. 2026-10-14 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-240

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

  16. 2026-10-22 published T-230 this result

    Daniel's smaller n303 packing, started from Ostashev's packing, certified exactly

    V3 C3 Upper bound confirmed superseded by T-240

    Daniel after Ostashev, Levy · Daniel n303 2026-10-22 · packet · register

  17. 2026-10-23 published T-239

    Kristiansen's smaller n303 packing, found from Daniel's packing, certified exactly

    V3 C3 Upper bound confirmed superseded by T-240

    Kristiansen after Daniel, Ostashev, Levy · Kristiansen n303 2026-10-23 · packet · register

  18. 2026-10-23 published T-240

    Couzo's 268 and 303 of #763, below T-174 and T-239, from Kaggle notebook packings

    V3 C3 Upper bound confirmed

    Couzo after Lavrentev, Tymchishin, Muglich, Polkovskyi, Daniel, Fang, de Winter, Levy · Couzo issue 763 2026-10-23 · packet · register