T-235: Hosono reports a Lean kernel proof that s(59)=8, on Daniel's mixed-measure checker

V0 C0 Formalization recorded

2026-10-11 published · Hosono after Daniel, Levy, Stromquist, Nagamochi, Burns, Massaccesi · n=59

Hosono (wand125) reports a Lean 4 kernel proof that s(59)=8, a formalization of T-066, whose lower half this record holds on a replay of Daniel's zmx2 over the same cover. Its theorem, SquarePacking.s59_eq_8 : minSide 59 = 8, says that the least side of a square holding 59 closed unit squares, each translated and rotated, with pairwise disjoint interiors, is 8; the 8×8 grid attains it.

The lower half, s59_ge_8, applies Daniel's le_minSide_mixed to T-066's mixed cover, 26,308 points and 5,240 segments of [0,8]^2 with masses w/10^8 and total below 59, whose D4 invariance and total are checked by decide +kernel, through a box tree over 80 x 80 root cells of the D4 region: 43,154 generated Part files and 290 Roots files in 290 batches, every chunk one decide +kernel of ZMTreeM.checkM, proved sound once, on Daniel's library used unchanged from evand/square-packing. The source reports the axioms propext, Classical.choice and Quot.sound, no sorry and no native_decide, and a run of about 862 CPU-hours, of which it publishes a per-task receipt; the generated files and the axiom output are not published. Nothing here has built it.

Hosono after Daniel, square-packing, 11 October 2026. The commit names Claude as co-author.

Significance, composition and next rung
Significance
A proof-assistant route to a value T-066 holds on a complete replay, by the same cover and the same author's checker family checked in Lean's kernel instead: a citable detail that changes no theorem.
Composition
One cited entry, the source's report (E-n059-wand125-lean-kernel-report), which claims the exact value in Lean, the grid inside the proof. T-066's zmx2 replay is not cited: it is T-066's evidence, and a kernel check of the same cover is what this entry adds. No build is retained here, so V0; no review has read it, so C0.
Next rung
C1 needs the stage 4 mathematical review of the proof, which starts from the packet. V3 and C3 need a complete build here or by a third party retained here, from the retained scripts and Daniel's library staged from the 7 October evand packet, with its axiom receipt (think-cs9x): about 862 CPU-hours by the source's receipt, with 9.8 GB per Part process and 35 GB for the last two modules, so it is held above the owner's 40 CPU-hour item cap and this host. A build of Pts.lean alone decides the cover's data facts in Lean and moves no rung.
Unfinished confirmations
C1 (think-xk3f): the stage 4 mathematical review of s59_eq_8, its statement, the batch structure and the generator, read from the retained packet. Not priced.

C3 (think-cs9x): a complete build of the 43,444 generated modules, Cov.lean and S59Lower.lean from the retained scripts on the library at 1718a580, compared with SOURCES.sha256, with its axiom receipt, here or by a third party whose build is retained here. About 862 CPU-hours (priced 2026-10-23).
Novelty
previously-published Present in an identified source

The case

Case record

n=59

8
789
7.6818.681
nn+1

Proven

s(59)=8

  • optimal
  • exact

Citation record n-059

lowerHosono after Daniel, Levy et al. 2026, GitHub (confirmed T-066)

The case record

LowerUpper
Verified88
Reported88
Gap0 solved: the verified bounds meet

Results on the case

11 results in the register on n=59, 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-066

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

  3. 2026-09-27 published T-046

    Rectangle-density lower bounds verified at 48 counts in n=18…95

    V3 C3 Lower bound confirmed superseded by T-066

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

  4. 2026-09-28 published T-070

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

    V3 C3 Lower bound confirmed superseded by T-066

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

  5. 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

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

  6. 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-066

    Karakuş · Karakuş 2026 · source · register

  7. 2026-10-01 published T-066

    s(59)=8, by a mixed cover of points and grid-line segments

    V3 C3 Optimality confirmed

    Hosono after Daniel, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 exact covers 2026-10-01 · packet · source · review · register

  8. 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

  9. 2026-10-11 published T-235 this result

    Hosono reports a Lean kernel proof that s(59)=8, on Daniel's mixed-measure checker

    V0 C0 Formalization recorded

    Hosono after Daniel, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 n59 Lean kernel 2026-10-11 · packet · source · register

  10. 2026-10-12 published T-261

    Reported grade-C local minima for 233 source configurations of field degree at most 4

    V3 C1 Restricted optimality incomplete

    Daniel after Schadt, Ellsworth, Levy · Daniel exact and local reports 2026-10-12 · packet · packet · register

  11. 2026-10-13 published T-180

    Closed-form lower bound s(N)≥a(N) for every non-square N≥49, reported

    V0 C1 Lower bound reviewed on this case, superseded by T-066

    Hosono · wand125 closed form 2026-10-14 · packet · packet · register