T-063: s(61)=8, by monotonicity from T-062

V3 C3 Optimality confirmed

2026-09-28 published · Daniel after Burns, Massaccesi · n=61

s(61)=8, as a corollary of s(60)=8 (T-062), which Daniel published with it on 28 September 2026.

Removing a square from a packing leaves a packing, so s(61) is at least s(60), and the 8×8 grid holds 61 unit squares. The s(60) cover's total, 59.86, is below 61 too, so its certificate decides both counts.

T-062's lower half was replayed here in full on 2 October 2026, and this value with it. Hosono's s(59)=8 (T-066), replayed here the same day, gives it a second route by the same deduction, and the same source's family s(k^2 - 3) = k (T-064) states it again at k = 8, by a separate certificate, replayed here on 3 October with the reduction built. Hosono's point-only cover for s(61) itself, which Daniel also reports certifying, was replayed here on 2 October by Daniel's zmx2, VERIFIED-D4 over all 6,400 roots: a route that uses points only, on a cover built by someone else.

Daniel, evand/square-packing, building on Burns's and Massaccesi's method. The source's CREDITS.md says the work was produced by Claude (Anthropic) in a single session under human direction.

Significance, composition and next rung
Significance
s(61)=8, an exact value for a case that was open, by one line of monotonicity from T-062. The score is of the claim, and the claim settles a case: S3, as T-002 and T-016, the register's monotone corollaries of S3 premises, carry their premises' S3 to the counts they move (T-156, from T-155's S1, is S1), and as T-144 carries five counts at S3. The derivation's triviality is recorded in composition and next_rung, which give it nothing of its own, and not in the score; the S1 anchor, a routine consequence, is for an entry that establishes nothing the record did not hold, as T-129's custody is. Changed from S1 on 11 October: the 2 October review of s(60) had confirmed S1, and the 1 October process review had left the pair with T-016 unexplained.
Composition
Derived, and the minimum is set by its premise. The inputs are the lower half of T-062, E-n060-evand-mixed-cover-zmx2-replay (interval-certified, replayed here), whose scope takes in n=61 because the cover's total is below 61; monotonicity by deletion, E-n061-evand-derived-report, read and found sound; and the 8×8 grid, E-basic-grid-upper. It stands at T-062's V3/C3 and never above it. Hosono's s(59)=8 (T-066) is a second route under the same checker.

So is Hosono's separate point-only cover for s(61)=8, replayed here by zmx2 (E-n061-wand125-point-cover-zmx2-replay): a second route by the source's pinned checker, the same checker as T-062's, so no second method. Daniel's reports of certifying that cover with zeromargin.py and zmcheck (E-n061-wand125-point-cover-evand-replay-report) are not replayed here.
Next rung
Nothing of its own: this entry rises with T-062. Hosono's point-only cover was replayed here by zmx2 (think-hxrz); replaying Daniel's zeromargin.py or zmcheck on it would give s(61)=8 a route that rests neither on zmx2 nor on T-062's cover.
Novelty
previously-published Present in an identified source

The case

Case record

n=61

8
789
7.8108.810
nn+1

Proven

s(61)=8

  • optimal
  • exact

Citation record n-061

lowerDaniel after Burns, Massaccesi 2026, GitHub (confirmed T-063)

The case record

LowerUpper
Verified88
Reported88
Gap0 solved: the verified bounds meet

Results on the case

11 results in the register on n=61, 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-063

    Nagamochi · Nagamochi 2005 · source · register

  2. 2018 published T-087

    s(37)≥53/2+22−1 and s(61)≥73/2+22−1, by optimal piercing

    V3 C1 Lower bound reviewed superseded by T-063

    Bašić, Slivková · Basic-Slivkova 2018 · source · register

  3. 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

  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-063

    Hosono 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-063

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

  6. 2026-09-28 published T-063 this result

    s(61)=8, by monotonicity from T-062

    V3 C3 Optimality confirmed

    Daniel after Burns, Massaccesi · evand square-packing 2026-10-01 · packet · packet · packet · source 1 · source 2 · review 1 · review 2 · register

  7. 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

  8. 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-063

    Karakuş · Karakuş 2026 · source · register

  9. 2026-09-30 published T-064

    s(k2−3)=k for every integer k from 6 up; k=6…18 are the cases held here

    V3 C3 Optimality confirmed on this case, second certificate

    Daniel after Burns, Massaccesi · evand square-packing 2026-10-01 · packet · packet · packet · packet · source 1 · source 2 · review 1 · review 2 · register

  10. 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

  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-063

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