T-225: Daniel's solved, regularized views at 204, 227, 229 and 260, each the smallest side reported there

V3 C3 Upper bound confirmed

2026-10-20 published · Daniel after Couzo, de Winter, Polkovskyi, Levy · n=204,227,229,260

Four complete rational source certificates report finite upper-bound improvements at the exact sides they state: s(204)≤14.808642840591493923068442871459, s(227)≤15.563625652325149084792443723702, s(229)≤15.650161513876431064009548865321 and s(260)≤16.645753250519812194746296653316.

The four certificates and their 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 reproduced it, decided each certificate again on a clean-room checker of its own, and found no blocking defect.

Each certificate is a display-regularized view, in Daniel's regularized record lists, of a packing already reported, solved to its exact side, and lies below that packing's certificate: by 1.39e-9 at 204 and 2.51e-11 at 260 below Couzo's #678 certificates (T-223), by 1.76e-11 at 227 below Couzo's #672 certificate (T-227), and by 1.91e-11 at 229 below Daniel's #674 update (T-199). Each side lies below the verified upper bound at the next count, so each bound is new.

Each certificate's JSON reports it VALID under the source's checkers and verified at 80 digits, prints S_cert, the side its certificate's header states, and S_exact, the 50-digit side of the solved packing it rounds up, and classes the view at level 2, same packing traversable without expansion, by a path test that samples angle moves and that the method log says is not a continuous proof. The commit says the six refreshed counts were certified and regularized, and of 229 that the polished side is 2e-11 below the posted one, the exact optimum of the same packing; each JSON says it is not a new bound. The checkers are byte-identical to the copies the n183 packet retains. Those statements are the author's; no source program ran here.

Credit the packings to their finders (at 227 the source's list names Couzo, whose #672 refines de Winter's packing): Couzo's at 204 (#678, T-223, which his source credits to Polkovskyi's construction) and 260 (#678, T-223, his arrangement from a search seeded with Daniel's exact-form certificate of de Winter's #668 packing); de Winter's at 227 (#668, T-196) as refined in Couzo's #672 report (T-227; who made the refinement the source does not say); and Daniel's own at 229 (#674, T-199, from Couzo's #672 packing, which refines de Winter's).

Daniel (https://github.com/evand/square-packing) refreshed each packing from his store, solved it to the exact side stated (at 229 after a polish), regularized it for display at that side and wrote the certificate. His credits say the repository's work was produced by Claude (Anthropic) under human direction.

Significance, composition and next rung
Significance
Smaller finite construction sides at 204, 227, 229 and 260, each the solved exact side of a packing already reported (Couzo's #678 at 204 and 260 and his #672 at 227, Daniel's #674 at 229), 1.76e-11 to 1.39e-9 below that packing's certificate and regularized for display: a citable detail of each case that moves no theorem, S2 as T-146 is. At 227 the drop of 1.71e-4 below T-196 is #672's (T-227), not this entry's. No lower bound or optimum. Drafted at intake, confirmed by review A of #716 and by the 21 October stage 4 review.
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.
Regularizations
n = 204: a regularization of T-223’s packing by Daniel (conservative; solved to its side; the regularizer changed no angle, as its source reports; identity: the source’s claim; nearest centres one to one; 58 squares moved, at most 0.442; turns up to 0.159°).

n = 227: a regularization of T-227’s packing by Daniel (conservative; solved to its side; the regularizer changed no angle, as its source reports; identity: the source’s claim; nearest centres one to one; 16 squares moved, at most 0.168; turns up to 2.542°).

n = 229: a regularization of T-199’s packing by Daniel (conservative; solved to its side; the regularizer changed no angle, as its source reports; identity: the source’s claim; nearest centres not one to one).

n = 260: a regularization of T-223’s packing by Daniel (conservative; solved to its side; the regularizer changed no angle, as its source reports; identity: the source’s claim; nearest centres not one to one).
Regularized drawings
n = 204: a regularization of T-225’s packing by Levy (regularize_axis_components/2; at its own side; identity: measured here; nearest centres one to one; 0 squares moved, at most 1.57542e-17; no square turned).

n = 227: a regularization of T-225’s packing by Levy (Daniel's search/regularize (MIT), evand/square-packing@675a5ea, conservative, coincide, through devtools.regularize_evand; the project’s modifications: same-side exact re-solve (devtools.regularize_same_side); at its own side; 1 free angle moved; identity: measured here; nearest centres one to one; 1 square moved, at most 0.0509347; no square turned).

n = 229: a regularization of T-225’s packing by Levy (regularize_grid_slack/1: Daniel's coincidence placement (evand/square-packing search/regularize reg.coincidences and reg.place, MIT), ported to start from the witness's exact frame and to keep its contacts, then the same-side exact re-solve, through devtools.regularize_grid_slack; the project’s modifications: port of his coincidence placement (regularize_grid_slack/1) rather than his code, same-side exact re-solve (devtools.regularize_same_side); at its own side; identity: measured here; nearest centres one to one; 58 squares moved, at most 0.0381281; no square turned).

n = 260: a regularization of T-225’s packing by Levy (regularize_axis_components/2; at its own side; identity: measured here; nearest centres one to one; 0 squares moved, at most 1.251e-19; no square turned).
Novelty
previously-published Present in an identified source

The cases

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

n=227

15.0615.564
151617
15.06716.067
nn+1

Proven

15.06880≤s(227)≤15.563626

  • exact

Citation record n-227

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

upperde Winter et al., GitHub (confirmed T-225)

Open

  • optimality

The case record

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

n=229

15.1315.650
151617
15.13316.133
nn+1

Proven

15.13728≤s(229)≤15.650162

  • exact

Citation record n-229

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

upperDaniel 2026, GitHub (confirmed T-225)

Open

  • optimality

The case record

Case record

n=260

16.1216.646
161718
16.12517.125
nn+1

Proven

16.12849≤s(260)≤16.645754

  • exact

Citation record n-260

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

upperCouzo & Daniel, GitHub (confirmed T-225)

Open

  • optimality

The case record

Results on these cases

19 results in the register on n=204,227,229,260, oldest first, each with what it established and how it stands now.

  1. 2005 published T-007 · n=204,227,229,260

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

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

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-09-04 published T-085 · n=204,227,229,260

    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 · n=204,227,229,260

    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 · n=204,227,229,260

    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 these cases, 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 · n=204,227,229,260

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

    V3 C3 Upper bound confirmed on these cases, superseded by T-225

    Levy after Daniel · register

  6. 2026-10-12 published T-162 · n=204

    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 · n=204

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

    V3 C3 Upper bound confirmed on these cases, 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 · n=204,227,229,260

    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 · n=204

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

    V3 C3 Upper bound confirmed on these cases, 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 · n=204

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

    V3 C3 Upper bound confirmed on these cases, 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-196 · n=227,229,260

    de Winter reports three smaller rational upper bounds at 227, 229 and 260

    V3 C3 Upper bound confirmed superseded by T-225

    de Winter after Levy · de Winter upper bounds 2026-10-17 · packet · register

  12. 2026-10-17 published T-198 · n=229

    Daniel's opening n229 dilation certificate, after Couzo and de Winter

    V3 C3 Upper bound confirmed superseded by T-225

    Daniel after Couzo, de Winter, Levy · Daniel n229 dilation 2026-10-17 · packet · register

  13. 2026-10-17 published T-226 · n=204

    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

  14. 2026-10-17 published T-227 · n=227,229

    Couzo's refinements of de Winter's 227 and 229, below T-196 at both

    V0 C0 Upper bound recorded superseded by T-225

    Couzo after de Winter, Daniel, Levy · Couzo issue 672 2026-10-17 · packet · packet · register

  15. 2026-10-18 published T-199 · n=229

    Daniel's smaller n229 update, replacing the opening certificate

    V3 C3 Upper bound confirmed superseded by T-225

    Daniel after Couzo, de Winter, Levy · Daniel n229 dilation update 2026-10-18 · packet · register

  16. 2026-10-18 published T-223 · n=204,260

    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

  17. 2026-10-18 published T-228 · n=204

    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

  18. 2026-10-20 published T-225 this result · n=204,227,229,260

    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

  19. 2026-10-22 published T-229 · n=204

    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