T-217: Mixed rectangle-measure lower bound s(110)≥1073/100 reported, on the 201-direction net

V0 C0 Lower bound recorded

2026-10-16 published · Hosono after Tokoharu and Levy · n=110

A rectangle measure of wand125/square-packing, published on 16 October 2026 and reported in jlevy/squares#446, is reported to prove s(110)≥1073/100 = 10.73.

The certificate, mixed_n110_L1073, is a density of 872 uniform rectangles in D4 orbits, and no point mass, of total mass 10999999/100000, on the net its candidate declares, the standard net of 201 half-angle tangents of step 83/40000 at core side 9977/10000. Since 9977/10000 (1 + 83/40000) = 399908091/400000000 < 1, and the last tangent 83/200 is past tan(pi/8), every unit square contains a concentric core at a net angle strictly in its interior. The search that found it started from a published certificate at a smaller count, mapped to this side and re-solved by linear programming (lifted, the source's provenance/search-notes.md); the certificate is the measure alone.

The source reports every such core capturing mass at least one at all 201 directions, by sqverify-proof-net, its copy of this repository's sqverify_fast changed to read the declared net, in two complete runs, and a control with every mass scaled by 197/200 refused at 32 sampled directions.

The value is above the reported lower bound at n=110, T-180's 10.600000000000..., Hosono's closed form (jlevy/squares#600), by 0.1300, and above the verified one, 10.5124921972... (Karakuş's strip bound, T-083 and T-084), by 0.2175; the bundle's own README compares it with the latter.

Here the maintained readers accepted its exact mass, declared-net and check2 premises from the retained release asset. No complete replay has run here, so the value stands as reported.

wand125 after Tokoharu and Levy, square-packing. The source says parts of the work were produced with AI assistance under human direction.

Significance, composition and next rung
Significance
Scored as a claim: if a complete replay passes, it is the strongest lower bound on record at n=110, 0.1300 above the reported lane, by the certificate kind and standard net of T-082, T-090 and T-091, with no new technique, at S3 as T-176 to T-178 are.
Composition
One reported certificate on its reported entry. The source's check is a copy of this repository's sqverify_fast crate with one change, so a sqverify-fast replay here would be re-implemented sharing the producer's components, as T-104's is, and no second implementation stands beside it.
Next rung
C3 needs a complete sqverify-fast census at all 201 directions of the retained candidate, with its whole-net control receipt (the 99/100 mutant at every direction, FC-1) and a review that reads this certificate, by the checklist of the 6 October declared-net soundness review. The census runs in think-f40c, priced at about 2.47 to 2.83 CPU-hours from the source's receipt.
Unfinished confirmations
C3 (think-f40c): a complete sqverify-fast census at all 201 directions of the retained candidate, with its whole-net control receipt (the 99/100 mutant at every direction, FC-1) and a review that reads this certificate, by the checklist of the 6 October declared-net soundness review. About 2.47 CPU-hours, up to about 2.83 (priced 2026-10-17).
Novelty
previously-published Present in an identified source

The case

Case record
Regularized by the Squares Project with its own axis tool (regularize_axis_components/2)
As published
The packing as published, Couzo 2026 [PingYou PR 574 certificates 2026-10-13]

n=110

10.5110.997
101112
10.48811.488
nn+1

Proven

10.51249≤s(110)≤10.996784

  • exact

Citation record n-110

lowerKarakuş 2026, arXiv corrects Nagamochi 2005 (confirmed T-083)

upperCouzo et al., GitHub (confirmed T-174)

Open

  • optimality

The case record

LowerUpper
Gap0.48429119…

Results on the case

8 results in the register on n=110, 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-083 and T-180 (reported)

    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-056

    Smaller packings for 49 counts from n=68 to 307, each certified two independent ways

    V3 C3 Upper bound confirmed superseded by T-174

    Couzo · franciscouzo square-packing 2026-09-27 · packet · register

  4. 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

    Karakuş · Karakuş 2026 · source · register

  5. 2026-10-05 published T-098

    Exact optima of 48 known-best packings: s(n) ≤ S', 3.5e-13 to 5.0e-11 below each printed side

    V3 C3 Upper bound confirmed on this case, superseded by T-174

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

  6. 2026-10-13 published T-174

    Tighter certificates at 68 counts from PingYou Ltd, of others' packings and its own

    V3 C3 Upper bound confirmed

    PingYou Ltd after Friedman, Ellsworth, Daniel, Xu, Barnett, Couzo, Ostashev, Chaoweeraprasit, Gupta, Fang, Polkovskyi, Levy · PingYou PR 574 certificates 2026-10-13 · packet · register

  7. 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

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

  8. 2026-10-16 published T-217 this result

    Mixed rectangle-measure lower bound s(110)≥1073/100 reported, on the 201-direction net

    V0 C0 Lower bound recorded

    Hosono after Tokoharu and Levy · wand125 fine-net lower bounds 2026-10-16 · packet · register