T-003: The sixteen-point set's unavoidability ceiling lies in [4426213/1000000,4427/1000)

V3 C3 method limit confirmed

2026-08-31 established · Levy after Bentz · n=17,18

The sixteen-point set's unavoidability ceiling lies in [4426213/1000000, 4427/1000): certification at the left endpoint, an exact escaping pose at the right, with the top strips' a + 2b <= 2*sqrt(2) hypothesis identifying the closing mechanism at 753/250 + sqrt(2), inside the bracket.

Significance, composition and next rung
Significance
Sharpens what T-001's construction can and cannot give; the exact equality claim at 753/250 + sqrt(2) remains analysis until the Q(sqrt 2) certificate lands.
Composition
Compound: the lower side of the bracket carries T-001's two methods and the refutation side rests on the interval audit alone. Both are machine-replayed here, so the bracket is C3; a second method on one side does not change the rung. The equality reading is deliberately not this claim.
Next rung
think-iye2: the shared certifier generalized to a Q(sqrt 2) scalar certifies at the ceiling exactly and an exact escape family above it turns the bracket into an equality at C3.
Novelty
apparently-novel Not found in the recorded search, subject to its stated gaps

The cases

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 Kleddamag et al. 2026, GitHub (confirmed T-093)

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

Open

  • optimality

The case record

Case record

n=18

4.704.823
456
4.2435.243
nn+1

Proven

4.70500≤s(18)≤4.822876

  • exact

Citation record n-018

lowerwand125 after Tokoharu, Levy et al. 2026, GitHub (confirmed T-102)

upperHämäläinen 1980, Squares in Squares

Open

  • optimality

The case record

LowerUpper
Gap72−241200≈ 0.11787565…

Results on these cases

28 results in the register on n=17,18, oldest first, each with what it established and how it stands now.

  1. 2005 published T-007 · n=17,18

    s(n)≥min(⌈n⌉,n−2⌊n⌋+1+1) for 4≤n≤324

    V0 C1 lower bound incomplete on these cases, superseded by T-093 and T-102

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-08-21 published T-015 · n=17

    s(17)≥22529/5000=4.5058

    V3 C3 lower bound confirmed superseded by T-093

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

  3. 2026-08-21 published T-016 · n=18

    s(n)≥22529/5000 for n=18,19, by monotonicity from T-015

    V3 C3 lower bound confirmed superseded by T-102

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

  4. 2026-08-31 established T-001 · n=17

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

    V3 C3 lower bound confirmed superseded by T-093

    Levy after Bentz · register

  5. 2026-08-31 established T-002 · n=18

    s(18)≥4426213/1000000, by monotonicity from T-001

    V3 C3 lower bound confirmed superseded by T-102

    Levy after Bentz · register

  6. 2026-08-31 established T-003 this result · n=17,18

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

    V3 C3 method limit confirmed

    Levy after Bentz · register

  7. 2026-09-04 established T-019 · n=17,18

    s(n)≥459/100=4.59 for n=17,18,19

    V3 C3 lower bound confirmed superseded by T-093 and T-102

    Levy after Burns, Massaccesi · register

  8. 2026-09-04 published T-085 · n=17,18

    Nagamochi 2005, Lemma 1 is false for every container with a>3 and b>2

    V3 C3 correction confirmed

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

  9. 2026-09-18 established T-027 · n=18

    s(18)≥467/100=4.67

    V3 C3 lower bound confirmed superseded by T-102

    Levy after Burns, Massaccesi · register

  10. 2026-09-19 established T-028 · n=18

    s(18)≥187/40=4.675

    V3 C3 lower bound confirmed superseded by T-102

    Levy after Burns, Massaccesi · register

  11. 2026-09-19 established T-029 · n=18

    s(18)≥1871/400=4.6775

    V3 C3 lower bound confirmed superseded by T-102

    Levy after Burns, Massaccesi · register

  12. 2026-09-19 established T-030 · n=18

    s(18)≥4679/1000=4.679

    V3 C3 lower bound confirmed superseded by T-102

    Levy after Burns, Massaccesi · register

  13. 2026-09-20 published T-032 · n=17

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

    V3 C3 lower bound confirmed superseded by T-093

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

  14. 2026-09-21 published T-038 · n=17

    s(17)>461300/99853=4.6197910929…

    V3 C3 lower bound confirmed superseded by T-093

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

  15. 2026-09-21 published T-065 · n=17

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

    V3 C3 upper bound confirmed

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

  16. 2026-09-25 published T-039 · n=17

    s(17)>231001/50000=4.62002

    V3 C3 lower bound confirmed superseded by T-093

    Guzhou0806 after Kleddamag, Mira, Levy · Guzhou0806 n17 R052 · packet · source · review · register

  17. 2026-09-26 published T-040 · n=17

    s(17)>232001/50000=4.64002

    V3 C3 lower bound confirmed superseded by T-093

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

  18. 2026-09-27 published T-041 · n=17

    s(17)>466001/100000=4.66001

    V3 C3 lower bound confirmed superseded by T-093

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

  19. 2026-09-27 published T-045 · n=18

    Rectangle-density lower bounds replayed at 15 counts in n=18…78

    V3 C3 lower bound confirmed superseded by T-102

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

  20. 2026-09-27 published T-046 · n=18

    Rectangle-density lower bounds reported for 48 counts in n=18…95

    V0 C0 lower bound recorded superseded by T-102

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

  21. 2026-09-28 published T-042 · n=17

    s(17)>233009/50000=4.66018

    V3 C3 lower bound confirmed superseded by T-093

    Guzhou0806 after Kleddamag, Mira, Levy · Guzhou0806 n17 R067 · packet · source · review · register

  22. 2026-09-28 published T-043 · n=17

    s(17)>116511/25000=4.66044

    V3 C3 lower bound confirmed superseded by T-093

    Guzhou0806 after Kleddamag, Mira, Levy · Guzhou0806 n17 R068 · packet · source · review · register

  23. 2026-09-29 published T-058 · n=17,18

    Rectangle-certificate ceiling α·UB(n) proved for n=1..100; B·UB(n) on 64 grid rows

    V3 C3 method limit confirmed

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

  24. 2026-09-29 published T-083 · n=17,18

    s(n)≥1/2+n−⌊n⌋+1/4 for every nonsquare 8≤n≤324

    V3 C3 lower bound confirmed on these cases, superseded by T-093 and T-102

    Karakuş · Karakuş 2026 · source · register

  25. 2026-09-30 published T-093 · n=17

    s(17)>18641771/4000000=4.66044275

    V3 C3 lower bound confirmed

    Guzhou0806 after Kleddamag, Mira, Levy · Guzhou0806 n17 R071 · packet · source · review · register

  26. 2026-10-05 published T-096 · n=18

    Mixed rectangle-measure lower bound replayed at n=18, on a net the certificate declares

    V3 C3 lower bound confirmed superseded by T-102

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds finer net 2026-10-05 · packet · source · review · register

  27. 2026-10-06 published T-099 · n=18

    Mixed rectangle-measure lower bound verified at n=18, on a finer declared net

    V3 C3 lower bound confirmed superseded by T-102

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds finer net 2026-10-06 · packet · source 1 · source 2 · review · register

  28. 2026-10-06 published T-102 · n=18

    Mixed rectangle-measure lower bound verified at n=18, on the finest declared net yet

    V3 C3 lower bound confirmed

    wand125 after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds check2 2026-10-06 · packet · source · review · register