T-071: Mixed rectangle-measure lower bounds replayed at n=84…87

V3 C3 lower bound confirmed superseded by T-075, T-090, T-091 and T-094

2026-10-02 published · wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · n=84,85,86,87

Two rectangle densities of wand125/square-packing-bounds, checked at coverage one and published on 2 October 2026, prove s(84)≥47/5 = 9.4 and s(85)≥471/50 = 9.42. The n=85 certificate's mass is below 86 and 87 too, so it gives s(86)≥471/50 and s(87)≥471/50 as well: four counts in all.

Each certificate is a density of uniform rectangles with no point mass, of total mass n - 1/100000, at core side 9977/10000 on 201 net half-angles of step 83/40000: 661 rectangles at n=84 and 587 at n=85. Each is accepted at every oblique net angle by code/mixed_rotated_verify.cpp, the research copy of Tokoharu's verify.cpp that the source's s(50) certificate (T-048) and the five certificates of T-069 use, which accepts coverage at least 1 where Tokoharu's requires 10001/10000, and at angle zero by exact integer tables. The least oblique lower bounds are 1.00000000089 at n=84 and 1.0000000017 at n=85.

Both values exceed Green's reported 2 sqrt(2) + (247 + 12 sqrt(2))/41 = 9.2667335..., which this record holds at both counts by monotonicity from n=82, by more than 0.1332 and 0.1532; the source's own improvement figures are measured from 9.2667, below Green's value, and are not lower bounds. At n=86 and 87 the n=85 value is also above the rectangle certificates T-068 reports there, 1873/200 and 941/100.

Each certificate passed a complete replay here on 2 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.

wand125 after Tokoharu and Levy, square-packing-bounds. Registration was requested in a comment 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 four counts, n=84 to 87, past Green's reported value at n=84 and 85 by the widest margins over it on record, by the certificate kind of T-048 and T-069. Further sizes from one generator at S3; the 2 October review of these certificates proposed S3, which the replays leave standing.
Composition
Two primary certificates, each on its own reported entry and its own replay entry. n=86 and 87 take the n=85 certificate directly, its mass 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. Coverage is decided by that checker alone; the axis tables are a second implementation for one direction and not a second method.
Next rung
V4 and C4 need two adversarial AI reviews by distinct reviewers and a human oversight record; one adversarial review is retained. A second machine method would be a method-distinct decision of rotated coverage; the replays here run the source's own checker. The checker's controls were made on the n=37 certificate of the same kind.
Novelty
previously-published Present in an identified source

The cases

Case record

n=84

9.419.698
91011
9.16510.165
nn+1

Proven

9.41100≤s(84)≤9.698053

  • exact

Citation record n-084

lowerwand125 after Tokoharu, Levy et al. 2026, GitHub (confirmed T-094)

upperry-xu 2026, GitHub (confirmed T-125)

Open

  • optimality

The case record

Case record

n=85

9.469.743
91011
9.22010.220
nn+1

Proven

9.46000≤s(85)≤9.742641

  • exact

Citation record n-085

lowerwand125 after Tokoharu, Levy et al. 2026, GitHub (confirmed T-075)

upperFriedman 1997, Squares in Squares

Open

  • optimality

The case record

LowerUpper
Gap32−9925≈ 0.28264068…
Case record

n=86

9.509.821
91011
9.27410.274
nn+1

Proven

9.50300≤s(86)≤9.820566

  • exact

Citation record n-086

lowerwand125 after Tokoharu, Levy et al. 2026, GitHub (confirmed T-090)

upperry-xu 2026, GitHub (confirmed T-125)

Open

  • optimality

The case record

Case record

n=87

9.589.839
91011
9.32710.327
nn+1

Proven

9.58000≤s(87)≤9.838816

  • exact

Citation record n-087

lowerwand125 after Tokoharu, Levy et al. 2026, GitHub (confirmed T-091)

upperEllsworth et al., Squares in Squares (confirmed T-101)

Open

  • optimality

The case record

LowerUpper
Gap0.25881526…

Results on these cases

18 results in the register on n=84,85,86,87, oldest first, each with what it established and how it stands now.

  1. 2005 published T-007 · n=84,85,86,87

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

    V0 C1 lower bound incomplete on these cases, superseded by T-075, T-090, T-091 and T-094

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-09-04 published T-085 · n=84,85,86,87

    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. 2026-09-24 published T-089 · n=87

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

    V3 C3 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 · n=86

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

    V0 C0 lower bound recorded superseded by T-090

    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 · n=86

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

    V3 C3 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 · n=84,85,86,87

    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 · n=84,85,86,87

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

    V3 C3 lower bound confirmed on these cases, superseded by T-075, T-090, T-091 and T-094

    Karakuş · Karakuş 2026 · source · register

  8. 2026-10-01 published T-068 · n=86,87

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

    V3 C3 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. 2026-10-02 published T-071 this result · n=84,85,86,87

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

    V3 C3 lower bound confirmed superseded by T-075, T-090, T-091 and T-094

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

  10. 2026-10-02 published T-075 · n=85,86,87

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

    V3 C3 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

  11. 2026-10-03 published T-082 · n=86,87

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

    V3 C3 lower bound confirmed on these cases, superseded by T-090 and T-091

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

  12. 2026-10-04 published T-090 · n=84,86

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

    V3 C3 lower bound confirmed

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

  13. 2026-10-04 published T-091 · n=87

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

    V3 C3 lower bound confirmed

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

  14. 2026-10-05 published T-094 · n=84

    Mixed rectangle-measure lower bounds verified at n=67 and 84

    V3 C3 lower bound confirmed

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds 2026-10-05 · packet · source · review · register

  15. 2026-10-05 published T-101 · n=87

    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

  16. 2026-10-08 published T-125 · n=84,86

    Complete rational construction reports at 25 counts

    V3 C3 upper bound confirmed

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

  17. 2026-10-08 published T-130 · n=84,86

    Five follow-up rational refinements from Francisco Couzo

    V3 C3 upper bound confirmed

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

  18. 2026-10-09 published T-138 · n=84,86

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

    V3 C3 upper bound confirmed

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