T-048: s(50)≥37/5=7.4

V3 C3 lower bound confirmed

2026-09-28 published · wand125 after Daniel, Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · n=50,51

s(50)≥37/5 = 7.4, by wand125's mixed rectangle-density certificate of 28 September 2026. It exceeds Green's reported 2 sqrt(2) + 101/25 + 3 sqrt(14)/25 = 7.3174260 by more than 0.0825739888. The certificate's mass is below 51 too, so it gives s(51)≥37/5 as well.

The certificate is a D4-expanded rectangle density of 553 orbit representatives, total mass 4999999/100000 < 50, core side 9977/10000 and 201 net half-angles of step 83/40000. It is accepted at every oblique net angle by code/mixed_rotated_verify.cpp, a research copy of Tokoharu's verify.cpp that accepts coverage at least 1 instead of 10001/10000 and checks each net node's unit-square centre domain, and at angle zero by exact integer tables.

The source's complete replay was run here on 29 September 2026 on the pinned bundle, with the source's driver and checker unchanged: all 201 directions, each equal to the shipped record. This repository's exact audit checked the premises and the integrity of all 621 bundle files and all 200 oblique inputs. The replay runs the source's own algorithm and is not an independent decision of coverage.

wand125 after Evan Daniel and Tokoharu, square-packing-bounds, the n=50 measure resting on Tokoharu's format and checker. 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 n=50 by 0.317 over Nagamochi's closed form, and at n=51 by 0.236, and stands 0.0826 above Green's reported value at n=50. The two changes to Tokoharu's checker were read and found legitimate on 2026-09-28. A substantive case result at S3. The closed form has been a reported bound since Karakuş's finding (T-085, merged 2026-10-03), so the margins over the verified floor it left, Karakuş's general bound, are larger.
Composition
One certificate. E-n050-wand125-mixed-740-source-replay replays it in full with the source's own driver and checker: one interval-certified method, replayed here, C3. Coverage is decided by the source's C++ checker alone, and the axis tables are a second implementation for one direction and not a second method. n=51 takes the same certificate directly, its mass being below 51, so no step is added.
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 replay here runs the source's own checker. The checker's controls were made on the n=37 certificate of the same kind; devtools.audit_wand125_point_and_mixed mixed-control on this certificate would bind them to this measure as well.
Novelty
previously-published Present in an identified source

The cases

Case record

n=50

7.407.571
789
7.0718.071
nn+1

Proven

7.40000≤s(50)≤7.571429

  • exact

Citation record n-050

lowerwand125 after Daniel et al. 2026, GitHub (confirmed T-048)

upperSchadt 2025, Squares in Squares (reported)

Open

  • optimality

The case record

LowerUpper
Gap0.17142857…
Case record

n=51

7.477.690
789
7.1418.141
nn+1

Proven

7.47000≤s(51)≤7.690356

  • exact

Citation record n-051

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

upperry-xu 2026, GitHub (confirmed T-126)

Open

  • optimality

The case record

LowerUpper
Gap523−641300≈ 0.22035593…

Results on these cases

12 results in the register on n=50,51, oldest first, each with what it established and how it stands now.

  1. 2005 published T-007 · n=50,51

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

    V0 C1 lower bound incomplete on these cases, superseded by T-048 and T-090

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-09-04 published T-085 · n=50,51

    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. 2026-09-27 published T-046 · n=51

    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

  4. 2026-09-28 published T-048 this result · n=50,51

    s(50)≥37/5=7.4

    V3 C3 lower bound confirmed

    wand125 after Daniel, Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 point and mixed bounds 2026-09-28 · packet · source · review · register

  5. 2026-09-28 published T-070 · n=51

    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=50,51

    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=50,51

    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-048 and T-090

    Karakuş · Karakuş 2026 · source · register

  8. 2026-10-03 published T-082 · n=51

    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

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

  9. 2026-10-04 published T-090 · n=51

    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

  10. 2026-10-05 published T-101 · n=50,51

    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. 2026-10-08 published T-125 · n=51

    Complete rational construction reports at 25 counts

    V3 C3 upper bound confirmed on these cases, superseded by T-126

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

  12. 2026-10-08 published T-126 · n=51

    Undilated n51 construction over Q(sqrt2)

    V3 C3 upper bound confirmed

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