T-220: Daniel's finite sub-grid upper bound for 183 squares, after Couzo's n182 packing

V3 C3 Upper bound confirmed

2026-10-19 published · Daniel after Couzo; register seed data from Levy · n=183

s(183)≤13999580178736252502081470897571/1000000000000000000000000000000 = 13.999580178736252502081470897571 < 14, from the original rational certificate, printed safely upward as 13.999580178737. Independently re-verified here by the project's maintained exact geometry implementations relative to the producer's code, with complete all-pair/wall coverage and duplicate-square/outside-container controls. Credit Daniel after Couzo's n182 packing, through an explorer descendant, insertion, crossovers and refinement; crossover mates were not logged. The regularized display file is retained source history, unexecuted here.

Significance, composition and next rung
Significance
A complete rational certificate gives a sub-grid packing at n183, about 4.20e-4 below the retained side-14 grid. Full exact primary replay and the accepted independent mathematical review support this finite case result; no optimality or public priority is claimed. The review endorses S3.
Next rung
Finite feasibility is confirmed by independently re-implemented project geometry, with the common parser/conversion/Fraction/SAT/runtime limits disclosed. No additional primary geometry run is required. The case house was adopted at n183 on 2026-10-19, and both strong generators decided its witness in the same pull request. V4/C4 would require the prescribed accepted distinct reviews and human oversight; regularized/source-checker work is separate and optional for this bound.
Regularized drawings
n = 183: a regularization of T-220’s packing by Levy (Daniel's search/regularize (MIT), evand/square-packing@675a5ea, conservative, coincide, through devtools.regularize_evand; the project’s modifications: same-side exact re-solve (devtools.regularize_same_side); at its own side; 1 free angle moved; identity: measured here; nearest centres one to one; 24 squares moved, at most 0.357845; turns up to 6.23142°).
Novelty
previously-published Present in an identified source

The case

Case record
Regularized by the Squares Project with Daniel's regularizer (evand/square-packing, MIT)
As published
The packing as published, Daniel 2026 [Daniel n183 subgrid 2026-10-19]

n=183

13.5414.000
131415
13.52814.528
nn+1

Proven

13.54798≤s(183)≤13.999581

  • exact

Citation record n-183

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

upperDaniel 2026, GitHub (confirmed T-220)

Open

  • optimality

The case record

LowerUpper
Gap0.45159182…

Results on the case

6 results in the register on n=183, 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. 2026-09-29 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

  4. 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

  5. 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

  6. 2026-10-19 published T-220 this result

    Daniel's finite sub-grid upper bound for 183 squares, after Couzo's n182 packing

    V3 C3 Upper bound confirmed

    Daniel after Couzo; register seed data from Levy · Daniel n183 subgrid 2026-10-19 · packet · register