T-015: s(17)≥22529/5000=4.5058

V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

2026-08-21 published · Massaccesi after Burns · n=17

s(17)≥22529/5000 = 4.5058, by Massaccesi's 168-atom fractional unavoidable-set certificate on Burns's architecture: total mass 203/12 < 17 and mass at least 1 in every closed unit square of [0, 22529/5000]^2, reduced exactly to 181 rational directions and finitely many event cells.

It was replayed here by the source verifier and by an accumulation-independent repository instrument.

Massaccesi, building on Burns, in a blog post of 21 August 2026. Massaccesi marks the value "(?)".

Significance, composition and next rung
Significance
Raises the verified lower bound at n=17 by 79587/1000000 = 0.079587 over this project's sixteen-point certificate T-001 and closes the gap to the reported record to 0.1697; Massaccesi's result, which this repository replayed, checked by an independent accumulation, and audited lemma by lemma in two reviews.
Next rung
V4 and C4 need two adversarial AI reviews by distinct reviewers and a human oversight record, and none is retained.

A method-distinct certificate would be shown beside the rung as a second machine method: a pose-space interval branch-and-bound over (theta, x, y) with the true unit square and weighted atoms, on the pattern of cases/green17/interval_audit.py (note that this certificate is tight, with every row minimum exactly 1 on open cells, so a naive box-splitting audit will not terminate at event lines and needs the semicontinuity argument built in); or, short of that, retain a from-scratch whole-check evaluator (the BC-149, BC-150 or BC-151 scratch evaluators) as a repository case with a replay so the reduction is no longer single-sourced on the record. Rung 5 needs a proof-assistant formalization of the eleven-lemma argument in the BC-150 packet, reviewed by human experts.

Superseded as the verified lower bound on 2026-09-04 by T-019, which certifies 459/100 at n=17 with this project's denser certificate. This result stays true as stated and keeps its rungs; what changed is that the register no longer reads 22529/5000 as the strongest available at this size.
Novelty
previously-published Present in an identified source

The case

Case record

n=17

4.664.676
456
4.1235.123
nn+1

Proven

4.66044≤s(17)≤4.675531

  • exact

Citation record n-017

lowerGuzhou0806 after Overbeck et al. 2026, GitHub (confirmed T-093)

upperBidwell 1998, Squares in Squares (confirmed T-065)

Open

  • optimality

The case record

Results on the case

19 results in the register on n=17, 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-093 and T-153 (reported)

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-08-21 published T-015 this result

    s(17)≥22529/5000=4.5058

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Massaccesi after Burns · Burns–Massaccesi n17 · packet · register

  3. 2026-08-31 established T-001

    s(17)≥4426213/1000000=4.426213, from a sixteen-point unavoidable set

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Levy after Bentz · register

  4. 2026-08-31 established T-003

    The sixteen-point set's unavoidability ceiling lies in [4426213/1000000,4427/1000)

    V3 C3 Method limit confirmed

    Levy after Bentz · register

  5. 2026-09-04 established T-019

    s(n)≥459/100=4.59 for n=17,18,19

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Levy after Burns, Massaccesi · register

  6. 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

  7. 2026-09-20 published T-032

    s(17)≥461300/99999=4.61304613…, and beneath it Mira's s(17)≥4613/1000

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Guzhou0806, Mira-acc after Levy, Burns, Massaccesi · n17 weighted certificates 2026-09-20 · packet · register

  8. 2026-09-21 published T-038

    s(17)>461300/99853=4.6197910929…

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Overbeck after Levy, Mira-acc, Guzhou0806 · Kleddamag n17 certified bound · packet · source · review · register

  9. 2026-09-21 published T-065

    s(17)≤4.6755300936045509…, Bidwell's packing certified exactly

    V3 C3 Upper bound confirmed

    Overbeck after Levy, Mira-acc, Guzhou0806 · Kleddamag n17 certified bound · packet · source · review · register

  10. 2026-09-25 published T-039

    s(17)>231001/50000=4.62002

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Guzhou0806 after Overbeck, Mira-acc, Levy · Guzhou0806 n17 R052 · packet · source · review · register

  11. 2026-09-26 published T-040

    s(17)>232001/50000=4.64002

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Overbeck after Levy, Mira-acc, Guzhou0806 · Kleddamag n17 4.640020 · packet · source · review · register

  12. 2026-09-27 published T-041

    s(17)>466001/100000=4.66001

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Overbeck after Levy, Mira-acc, Guzhou0806 · Kleddamag n17 4.66001 · packet · source · review · register

  13. 2026-09-28 published T-042

    s(17)>233009/50000=4.66018

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Guzhou0806 after Overbeck, Mira-acc, Levy · Guzhou0806 n17 R067 · packet · source · review · register

  14. 2026-09-28 published T-043

    s(17)>116511/25000=4.66044

    V3 C3 Lower bound confirmed superseded by T-093 and T-153 (reported)

    Guzhou0806 after Overbeck, Mira-acc, Levy · Guzhou0806 n17 R068 · packet · source · review · register

  15. 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

  16. 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-093 and T-153 (reported)

    Karakuş · Karakuş 2026 · source · register

  17. 2026-09-30 published T-093

    s(17)>18641771/4000000=4.66044275

    V3 C3 Lower bound confirmed

    Guzhou0806 after Overbeck, Mira-acc, Levy · Guzhou0806 n17 R071 · packet · source · review · register

  18. 2026-10-12 published T-153

    Candidate proof that Bidwell's 1998 packing is optimal, s(17)=4.67553009360455…

    V0 C1 Optimality reviewed

    Overbeck after Levy, Ahmed, Mira-acc, Guzhou0806, Maaz · Overbeck n17 candidate 2026 · packet · register

  19. 2026-10-12 published T-154

    Fitzharding reports a Lean proof that s(17)=4.67553009360455…

    V3 C1 Formalization reviewed

    Fitzharding after Levy, Ahmed, MacIver · Fitzharding n17 Lean 2026 · packet · source · source build receipt · review 1 · review 2 · register