T-075: Mixed rectangle-measure lower bounds replayed at nine counts in n=83…96

V3 C3 lower bound confirmed

2026-10-02 published · wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · 9 cases, n=83 to 96

Six rectangle-density certificates that wand125/square-packing-bounds published on the afternoon of 2 October 2026 prove s(83)≥937/100 = 9.37, s(85)≥473/50 = 9.46, s(87)≥237/25 = 9.48, s(91)≥97/10 = 9.7, s(92)≥39/4 = 9.75 and s(96)≥249/25 = 9.96. A packing of 86 squares contains one of 85, and likewise at 88 and 93, so they also give s(86)≥473/50, s(88)≥237/25 and s(93)≥39/4.

Each is a density of 279 to 728 uniform rectangles in D4 orbits and no point mass, of total mass n - 1/100000, at core side 9977/10000 on 201 net half-angles of step 83/40000, of the kind and checker of T-069, T-071 and T-072. The source reports each accepted at all 200 oblique net angles by code/mixed_rotated_verify.cpp, its research copy of Tokoharu's verify.cpp at coverage threshold one, and at the axis by exact integer tables. Two supersede certificates this record held verified at the same count, at n=85 (T-071) and n=92 (T-069).

Each value is above what the record reported at its count: by 0.02 at n=83, over the linear certificate of T-073, and by 0.0025 to 0.095 at the others, over the source's rectangle certificates (T-068, T-074) and its earlier mixed ones. At n=96 it is the first certificate in this record above Nagamochi's 1 + sqrt(79) = 9.8882.... At n=83, 85 and 87 the source measures its improvement from 92667/10000, below Green's reported 9.2667335..., so those figures overstate the margin; the bounds are unaffected.

Each certificate passed a complete replay here on 2 and 3 October 2026 of the source's unchanged checker and per-angle functions on its pinned tarball: all 201 directions, each returning the certificate's own record. The replays run the source's own algorithm and are not an independent decision of coverage. sqverify-fast, this repository's clean-room measure verifier, also decided each at all 201 net directions of the retained candidate in its census of 3 October 2026, and on 6 October two mutants of each scaled below coverage one were refused: independently re-implemented, beside the reproduction with the producer's code. It shares no code with the source's checker and runs the same net-and-shrink method, so it is a second implementation and not a second method.

wand125 after Tokoharu and Levy, square-packing-bounds. Registration was requested in four comments of 2 October 2026 on jlevy/squares#282. The source says parts of the work were produced with AI assistance under human direction.

Significance, composition and next rung
Significance
Raised the verified lower bound at nine counts, n=83 to 96, the first above Nagamochi's value at n=96. Further sizes from the generator and checker of T-069, T-071 and T-072, with no new technique, at S3 as those are; the 2 October review of the afternoon certificates proposed S3, which the replays leave standing.
Composition
Six primary certificates, each on its own reported entry and its own replay entry. n=86, 88 and 93 take the n=85, 87 and 92 certificates directly, their masses being below those counts, so no step is added. Each replay runs the source's C++ checker unchanged: one interval-certified method, replayed here, C3. The axis tables are a second implementation for one direction and not a second method. Each certificate also has a third entry, sqverify-fast at all 201 net directions of the retained candidate: an independent implementation of the same method, recorded beside the rung and not a condition of it.
Next rung
V4 and C4 need two adversarial AI reviews by distinct reviewers and a human oversight record; one adversarial review is retained, written by the retaining lane before any replay. A second machine method would be a method-distinct decision of rotated coverage; the replays here, the source's own checker and sqverify-fast, run one method. The source's checker's controls were made on the n=37 certificate of the same kind; mixed-control n96 would put one on a certificate of this release. sqverify-fast's controls are on all six.
Novelty
previously-published Present in an identified source

The cases

This result concerns 9 cases, too many to draw one by one. Each is listed with the film’s bounds, the proved lower bound and the best known side, and links to its case record, where its packing and number line are drawn.

nProved lowerBest knownGapStatusRecords
839.3700009.6347580.26475764…open=frontier n-083.md
859.4600009.7426410.28264068…frontier n-085.md
869.5030009.8205660.31756573…frontier n-086.md
879.5800009.8388160.25881526…frontier n-087.md
889.6200009.8824520.26245103…frontier n-088.md
919.762500100.2375frontier n-091.md
929.7700000.23frontier n-092.md
939.8800000.12frontier n-093.md
969.9700000.03frontier n-096.md

Results on these cases

24 results in the register on these cases, oldest first
  1. 2005 published T-007 · 9 of these cases

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

    lower bound incomplete on these cases, superseded by T-075, T-081 (reported), T-082, T-090 and T-091

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-09-04 published T-085 · 9 of these cases

    Nagamochi 2005, Lemma 1 is false for every container with a>3 and b>2

    correction confirmed

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

  3. 2026-09-24 published T-089 · cases 83, 87

    s(83)≤9.63475764863195 and s(87)≤9.83881526994915, Chang's packings, certified exactly

    upper bound confirmed superseded by T-101

    Chang, Ellsworth after Cantrell, Hajba, Stenlund, Bidwell; Chang after Ellsworth, Cantrell, Schadt, Hajba, DeVincentis · Chang n83 2026-09-24 · Chang n87 2026-09-24 · packet · packet · register

  4. 2026-09-27 published T-046 · cases 86, 88, 91

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

    lower bound recorded superseded by T-090 and T-091

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

  5. 2026-09-28 published T-070 · case 86

    Rectangle-density lower bounds replayed at 25 counts in n=29…95

    lower bound confirmed superseded by T-090

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

  6. 2026-09-29 published T-058 · 9 of these cases

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

    method limit confirmed

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

  7. 2026-09-29 published T-083 · 9 of these cases

    s(n)≥1/2+n−⌊n⌋+1/4 for every nonsquare 8≤n≤324

    lower bound confirmed on these cases, superseded by T-075, T-081 (reported), T-082, T-090 and T-091

    Karakuş · Karakuş 2026 · source · register

  8. 2026-10-01 published T-068 · cases 86, 87, 88, 93

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

    lower bound confirmed on these cases, superseded by T-090 and T-091

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

  9. 2026-10-01 published T-069 · case 92

    Mixed rectangle-measure lower bounds replayed at n=37,65,66,90,92

    lower bound confirmed on these cases, superseded by T-082

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

  10. 2026-10-01 published T-074 · cases 88, 93

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

    lower bound confirmed on these cases, superseded by T-090 and T-091

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

  11. 2026-10-02 published T-071 · cases 85, 86, 87

    Mixed rectangle-measure lower bounds replayed at n=84…87

    lower bound confirmed superseded by T-075, T-090 and T-091

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds 2026-10-02 · packet · source · review · register

  12. 2026-10-02 published T-073 · case 83

    Linear-measure lower bounds replayed at n=83 and n=101…105

    lower bound confirmed on these cases, superseded by T-075

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 linear certificates 2026-10-02 · packet · source · review · register

  13. 2026-10-02 published T-075 this result · 9 of these cases

    Mixed rectangle-measure lower bounds replayed at nine counts in n=83…96

    lower bound confirmed

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds afternoon 2026-10-02 · packet · source 1 · source 2 · review · register

  14. 2026-10-03 published T-081 · case 96

    s(k2−4)=k for every integer k from 5 up; k=5…18 are the cases held here

    optimality reviewed

    Daniel after Burns, Massaccesi · evand square-packing 2026-10-03 · packet · packet · source · review · register

  15. 2026-10-03 published T-082 · 7 of these cases

    Mixed rectangle-measure lower bounds verified at 22 counts in n=51…96

    lower bound confirmed

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds 2026-10-03 · packet · packet · source · review · register

  16. 2026-10-04 published T-090 · cases 86, 88, 93, 96

    Mixed rectangle-measure lower bounds verified at 17 counts in n=42…96

    lower bound confirmed

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds 2026-10-04 · packet · source · review · register

  17. 2026-10-04 published T-091 · 5 of these cases

    Mixed rectangle-measure lower bounds verified at 17 counts in n=53…95

    lower bound confirmed

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds evening 2026-10-04 · packet · source · review · register

  18. 2026-10-05 published T-101 · cases 83, 87, 88

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

    upper bound confirmed

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

  19. 2026-10-07 published T-116 · case 88

    s(n)≤Sn at nine counts, from the second SQUISH update’s new rational packings

    upper bound confirmed on these cases, superseded by T-127

    Chaoweeraprasit after Ellsworth, Couzo and SQUISH · SQUISH second update 2026-10-07 · packet · register

  20. 2026-10-07 published T-124 · cases 91, 92, 93, 96

    Reported non-strict local minima for 178 source configurations

    restricted optimality recorded

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

  21. 2026-10-08 published T-125 · cases 86, 88

    Complete rational construction reports at 25 counts

    upper bound confirmed

    ry-xu · ry-xu square packing 2026 · packet · register

  22. 2026-10-08 published T-127 · case 88

    Fourteen rational refinements, seventeen complete source cases

    upper bound confirmed

    Gupta after Chaoweeraprasit, Daniel · Gupta rational refinements 2026-10-08 · packet · register

  23. 2026-10-08 published T-130 · case 86

    Five follow-up rational refinements from Francisco Couzo

    upper bound confirmed

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

  24. 2026-10-09 published T-138 · case 86

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

    upper bound confirmed

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