T-190: A tighter exact certificate for 237 squares from Francisco Couzo, below his issue-607 certificate

The case

Results on the case

16 results in the register on $n=237$$n=237$, 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)$s(n)\ge min(\lceil \sqrt{n}\rceil ,\sqrt{n-2\lfloor \sqrt{n}\rfloor +1}+1)$ for $4\le n\le 324$$4\le n\le 324$

   S3 V0 C1 Lower bound incomplete on this case, superseded by T-083 and T-180 (reported)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$$a>3$ and $b>2$$b>2$

   S3 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$$n=68$ to $307$$307$, each certified two independent ways

   S3 V3 C3 Upper bound confirmed superseded by T-190

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

4. 2026-09-29 published T-083

   s(n)≥1/2+n−⌊n​⌋+1/4​$s(n)\ge 1/2+\sqrt{n-\lfloor \sqrt{n}\rfloor +1/4}$ for every nonsquare $8\le n\le 324$$8\le n\le 324$

   S3 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

   S2 V3 C3 Upper bound confirmed on this case, superseded by T-190

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

6. 2026-10-07 published T-115

   s(n)≤Sn​$s(n)\le S_n$ at twelve counts, from the SQUISH update’s new and smaller rational packings

   S3 V3 C3 Upper bound confirmed superseded by T-190

   Chaoweeraprasit after Couzo and Ellsworth · SQUISH update 2026-10-07 · packet · register

7. 2026-10-08 published T-127

   Fourteen rational refinements, seventeen complete source cases

   S3 V3 C3 Upper bound confirmed on this case, superseded by T-190

   Gupta after Chaoweeraprasit, Daniel · Gupta rational refinements 2026-10-08 · packet · register

8. 2026-10-09 published T-134

   Six exact rational certificates from Couzo

   S3 V3 C3 Upper bound confirmed on this case, superseded by T-190

   Couzo after Polkovskyi, Chaoweeraprasit, Gupta, Xu, Daniel, Ellsworth, Levy · Couzo exact certificates 2026-10-09 · packet · register

9. 2026-10-09 published T-136

   Seventeen exact rational packings from SQUISH's third request

   S3 V3 C3 Upper bound confirmed on this case, superseded by T-190

   Chaoweeraprasit after Couzo, Xu, Göbel, Schadt, Ellsworth, Hajba, Levy · SQUISH third request 2026-10-09 · packet · register

10. 2026-10-10 published T-140

    Six more exact rational certificates from Couzo

    S3 V3 C3 Upper bound confirmed superseded by T-190

    Couzo after Chaoweeraprasit, Polkovskyi, Xu, Daniel, Ellsworth, Levy · Couzo certificates 2026-10-10 · packet · register

11. 2026-10-12 published T-161

    Exact rational certificates at 156, 176, 237 and 271 from Couzo

    S3 V3 C3 Upper bound confirmed superseded by T-190

    Couzo after Ostashev, Chaoweeraprasit, Fang, Daniel, Ellsworth, Levy · Couzo certificates 2026-10-12 · packet · register

12. 2026-10-13 published T-174

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

    S1 V3 C3 Upper bound confirmed on this case, superseded by T-190

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

13. 2026-10-13 published T-180

    Closed-form lower bound $s(N)\ge a(N)$$s(N)\ge a(N)$ for every non-square $N\ge 49$$N\ge 49$, reported

    S4 V0 C1 Lower bound reviewed

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

14. 2026-10-13 published T-183

    Polkovskyi's certificate for 237 squares, the smallest known side there when registered

    S3 V3 C3 Upper bound confirmed superseded by T-190

    Polkovskyi after Friedman, Daniel, Xu, Chaoweeraprasit, Barnett, Couzo, Ostashev, Ellsworth, Fang, Levy · Mishapolk records 2026-10-14 · packet · register

15. 2026-10-14 published T-189

    Couzo's refinement of Polkovskyi's 237, and fifteen beyond-horizon bounds

    S3 V3 C3 Upper bound confirmed superseded by T-190

    Couzo after Polkovskyi, Fang, Daniel, Ellsworth, Levy · Couzo certificates 2026-10-14 · packet · register

16. 2026-10-15 published T-190 this result

    A tighter exact certificate for 237 squares from Couzo, below his issue-607 certificate

    S2 V3 C3 Upper bound confirmed

    Couzo after Polkovskyi, Chaoweeraprasit, Daniel, Levy · Couzo n237 2026-10-15 · packet · register