T-142: Mixed rectangle-measure lower bound s(28)≥2297/400 reported, on a 2,073-direction declared net

V0 C0 lower bound recorded

2026-10-10 published · wand125 after Tokoharu and Levy · n=28

A rectangle measure of wand125/square-packing, published on 10 October 2026 and reported on no issue, is reported to prove s(28)≥2297/400 = 5.7425.

The certificate, mixed_n28_L57425, is a density of 631 uniform rectangles in D4 orbits, and no point mass, of total mass 2799999/100000, on a net its candidate declares: core side 4999/5000 and 2,073 half-angle tangents of step 1/5002, the net of T-102, T-103 and T-132. Since 4999/5000 (1 + 1/5002) = 25009997/25010000 < 1, and the last tangent 1036/2501 is past tan(pi/8), every unit square contains a concentric core at a net angle strictly in its interior.

The source reports every such core capturing mass at least one at all 2,073 directions, by sqverify-proof-net, its copy of this repository's sqverify_fast changed to read the declared net, and a control with every mass scaled by 197/200 refused at 32 sampled directions.

The value is above T-107's 1147/200 = 5.735, the verified and reported lower bound at n=28, by 3/400, and above the 287/50 that jlevy/squares#446 reported on 8 October, never adopted, by 1/400.

Here the maintained readers accepted its exact mass, declared-net and check2 premises, and sqverify-fast, this repository's clean-room measure verifier, verified it at eight sampled directions with the source's node counts and least certified bounds: a diagnostic, not a replay. No complete replay has run here, so the value stands as reported.

wand125 after Tokoharu and Levy, square-packing. The source says parts of the work were produced with AI assistance under human direction.

Significance, composition and next rung
Significance
Scored as a claim: if a complete replay passes, it is the strongest lower bound on record at n=28, 3/400 above T-107, by the certificate kind and declared net of T-102, T-103 and T-132, with no new technique, at S3 as T-102 to T-111 and T-132 are. V0/C0 says how far it stands, and the score gates nothing.
Composition
One reported certificate on its reported entry. The source's check is a copy of this repository's sqverify_fast crate with one change, so a sqverify-fast replay here would be re-implemented sharing the producer's components, as T-104's is, and no second implementation stands beside it.
Next rung
C3 needs a complete sqverify-fast census run at all 2,073 directions from a retained candidate, with its whole-net control receipt (the 99/100 mutant at every direction, FC-1) and a review that reads this certificate, by the checklist of the 6 October declared-net soundness review. The eight-direction sample prices the run and its controls at about 3.3 CPU-hours. The owner set its budget on 11 October 2026, and the run is queued in think-i85v after the regularization work (jlevy/squares#497).
Unfinished confirmations
C3 (think-i85v): a complete sqverify-fast census at all 2,073 directions from a retained candidate, with its whole-net control receipt (the 99/100 mutant at every direction, FC-1) and a review that reads this certificate, by the checklist of the 6 October declared-net soundness review. About 3.28 CPU-hours, up to about 4.5 (priced 2026-10-10).
Novelty
previously-published Present in an identified source

The case

Case record

n=28

5.735.824
567
5.2926.292
nn+1

Proven

5.73500≤s(28)≤5.824445

  • exact
  • rigid

Citation record n-028

lowerwand125 after Tokoharu, Levy et al. 2026, GitHub (confirmed T-107)

upperEllsworth 2025, Squares in Squares (confirmed T-101)

Open

  • optimality

The case record

LowerUpper
Gap0.08944461…

Results on the case

13 results in the register on n=28, 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-107

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

  3. 2026-09-22 published T-047

    s(11)≥381/100; s(n)≥1377/250 for n=26…28; s(n)≥571/100 for n=29…31

    V3 C3 lower bound confirmed superseded by T-107

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

  4. 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-107

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

  5. 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-107

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

  6. 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

  7. 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-107

    Karakuş · Karakuş 2026 · source · register

  8. 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-107

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

  9. 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-107

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

  10. 2026-10-05 published T-101

    Exact certificates of 77 catalogue packings: s(n) ≤ S', 1.2e-16 to 9.8e-15 above each side

    V3 C3 upper bound confirmed

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

  11. 2026-10-06 published T-107

    Mixed rectangle-measure lower bound verified at n=28, on a declared net

    V3 C3 lower bound confirmed

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds check2 2026-10-06 · packet · source · review · register

  12. 2026-10-07 published T-124

    Reported non-strict local minima for 178 source configurations

    V0 C0 restricted optimality recorded

    Daniel after Couzo · Daniel exact and local reports 2026 · packet · register

  13. 2026-10-10 published T-142 this result

    Mixed rectangle-measure lower bound s(28)≥2297/400 reported, on a 2,073-direction declared net

    V0 C0 lower bound recorded

    wand125 after Tokoharu and Levy · wand125 fine-net n28 n30 2026-10-10 · packet · register