T-145: s(40)>1340000/199529=6.7158157…, by a continuous-pose interval kernel

V3 C3 lower bound confirmed

2026-10-10 published · Guzhou0806 after wand125, Tokoharu, Levy, Stromquist, Burns, Massaccesi · n=40

s(40)>1340000/199529 = 6.715815746082023…, by Guzhou0806, published on 10 October 2026 as release n40-continuous-1340000-199529-20261010 of Guzhou0806/n40-square-packing and reported on jlevy/squares#485. It raises T-133's 335427/50000 by 72586117/9976450000 = 0.0072757…, from the same certificate.

The certificate is wand125's rect_n40_L67 rectangle density of T-068, unchanged, of mass 3999/100. Every closed square of side 199529/200000 inside [0, 67/10]^2, at every angle and every legal centre, captures mass at least 4999/5000, and 40 × 4999/5000 − 3999/100 = 1/500, so no packing fits at side 1340000/199529; compactness makes the bound strict.

A new interval kernel covers the continuous pose domain, centre and half-angle tangent together, in 43 closed slabs of t = tan(θ/2) over [10^-6, 83/200], by outward-rounded binary64 branch and bound with a concave-section integral bound and translation-derivative bounds; an exact integer certificate for horizontal squares of side 997643/1000000, which lie inside every side-B square at t ≤ 10^-6, covers the rest. No net, no transfer and no density peak are needed.

The source decided both parts with its two C++ kernels, in a local run and a GitHub Actions run.

Both were decided here on 10 October 2026: the two kernels, built from the retained source into the CI run's binaries, ran the axis certificate and all 43 slabs, every output equal to both release receipts apart from timing, and refused every synthetic density whose least capture is below the threshold: confirmed, reproduced with the producer's code.

This repository's exact audit, which shares no code with the release's, regenerated both kernel inputs and decided every finite step, and sqverify-fast decided the near-axis statement a second way on the original density. The 10 October review re-derived the kernel's lemmas and found no blocking defect. No second method decided the continuous cover.

Guzhou0806 after wand125, Tokoharu and Levy, n40-square-packing. The source credits the density to wand125, the rectangle-density method and the translation-derivative structure to Tokoharu, says the concave-section bound is informed by this repository's sqverify_fast, and gives Guzhou0806's contribution, the continuous-pose extension, the smaller-square coverage, the near-axis patch and the composition, as AI-assisted research; the comment says AI assisted the exploration, proof drafting, implementation, tests, packaging and the update under the author's direction.

Significance, composition and next rung
Significance
The strongest lower bound on record at n=40, 0.00728 above T-133 on the same certificate. The technique, an interval cover of the continuous pose domain with the angle as an interval dimension, is new to this record, dispenses with the net, the transfer and the density peak, and applies as it stands to every format T certificate the record holds, with the side and threshold as its parameters; it is one count and not yet a bound family. S3 by the precedent of T-133, with the technique noted, as the 10 October review suggests.
Composition
One certificate, wand125's rect_n40_L67, and three load-bearing parts. The continuous cover of the 43 slabs is decided by the release's continuous_pose.cpp, interval-certified, the producer's code, rebuilt here from reviewed source and replayed in full. The near-axis statement at side 997643/1000000 is decided by the release's axis_integer_grid.cpp, exact, replayed here, and again by sqverify-fast's exact axis-vertex sweep on the original density, which shares no code with it. The finite steps, both inputs' identity, the near-axis containment, the slab partition, the threshold and the counting margin, are decided by this repository's exact audit, independently re-implemented with respect to exact.py, and are recorded as structure.

The result takes the part closest to the producer's code: confirmed, reproduced with the producer's code. C3 rests on the complete replay of both kernels and its controls, and the kernel's lemmas on the 10 October review. No second method decides the continuous cover; the 401-direction run of sqverify-fast at the new parameters is a necessary condition it passed.
Next rung
V4 and C4 need a human oversight record: the two adversarial AI reviews by distinct reviewers are retained, the 10 October review and the 11 October final review (docs/project/reviews/review-2026-10-11-final-lower-bounds.md), both accepting. A method-distinct decision of the continuous cover would stand beside the rung: a first-party interval kernel with the angle as an interval dimension (GC-4 of the review, its specification), a W7 slice and a budget the owner sets.
Novelty
previously-published Present in an identified source

The case

Case record

n=40

6.716.828
678
6.3257.325
nn+1

Proven

6.71581≤s(40)≤6.828428

  • exact
  • rigid

Citation record n-040

lowerGuzhou0806 after wand125 et al. 2026, GitHub (confirmed T-145)

upperGöbel 1979, Squares in Squares

Open

  • optimality

The case record

LowerUpper
Gap22−541884199529≈ 0.11261137…

Results on the case

12 results in the register on n=40, 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-145

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-08-30 established T-013

    Goebel's n=40 packing: seven verified first-order flexes, each refused at second order

    V3 C3 rigidity confirmed

    Levy · register

  3. 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; chelokot · Karakuş 2026 · chelokot Nagamochi counterexample 2026 · packet · register

  4. 2026-09-22 published T-044

    Weighted point lower bounds for ten counts in n=26…72, plus seven from the same files

    V3 C3 lower bound confirmed superseded by T-145

    wand125 after Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 point bounds 2026 · packet · source · review · register

  5. 2026-09-27 published T-045

    Rectangle-density lower bounds replayed at 15 counts in n=18…78

    V3 C3 lower bound confirmed superseded by T-145

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 rectangle bounds 2026 · packet · packet · source · review · register

  6. 2026-09-27 published T-046

    Rectangle-density lower bounds reported for 48 counts in n=18…95

    V0 C0 lower bound recorded superseded by T-145

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 rectangle bounds 2026 · wand125 rectangle bounds 2026-09-28 · packet · packet · register

  7. 2026-09-29 published T-058

    Rectangle-certificate ceiling α·UB(n) proved for n=1..100; B·UB(n) on 64 grid rows

    V3 C3 method limit confirmed

    wand125 after Tokoharu, Daniel · wand125 tools 2026 · packet · register

  8. 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 on this case, superseded by T-145

    Karakuş · Karakuş 2026 · source · register

  9. 2026-10-01 published T-068

    Rectangle-density lower bounds verified at 34 counts in n=19…95

    V3 C3 lower bound confirmed on this case, superseded by T-145

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 rectangle bounds 2026-10-01 · packet · source · review · register

  10. 2026-10-01 published T-074

    Rectangle-density lower bounds replayed at 31 counts in n=19…95

    V3 C3 lower bound confirmed on this case, superseded by T-145

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 rectangle bounds 2026-10-01 · packet · packet · source · review · register

  11. 2026-10-10 published T-133

    s(40)>335427/50000=6.70854, by a clipped-corner transfer on a 401-direction net

    V3 C3 lower bound confirmed superseded by T-145

    Guzhou0806 after wand125, Tokoharu, Levy, Stromquist, Burns, Massaccesi · Guzhou0806 n40 clipped corner 2026-10-10 · packet · packet · source 1 · source 2 · review · register

  12. 2026-10-10 published T-145 this result

    s(40)>1340000/199529=6.7158157…, by a continuous-pose interval kernel

    V3 C3 lower bound confirmed

    Guzhou0806 after wand125, Tokoharu, Levy, Stromquist, Burns, Massaccesi · Guzhou0806 n40 continuous pose 2026-10-10 · packet · packet · source 1 · source 2 · review · register