$n=303$$n=303$

s(303) — Square Packing Case

Hosono’s closed form, 14 October 2026. Hosono’s closed form (wand125, 13 October 2026, T-180) states $s(N)\ge a(N)$$s(N)\ge a(N)$ for every non-square $N\ge 49$$N\ge 49$, from a measure of line segments on 34 intervals of the fractional part. At $n=303$$n=303$, $k=17$$k=17$ and interval 19 give $a(303)=17.461986185132785625652399664177\dots$$a(303)=17.461986185132785625652399664177\dots$, so the reported lower bound here is now $s(303)\ge 17.461986185132$$s(303)\ge 17.461986185132$, rounded down, above Nagamochi’s closed form, $17.43167672515$$17.43167672515$. The source replayed its certificate with its own checker; no record of it has been replayed here, so the verified lower bound is unchanged. The source states that its search, certificates, checkers and text were produced with AI assistance (Claude and Codex), under the direction of and reviewed by Hosono.

House adoption, 16 October 2026. Polkovskyi’s tighter certificate, after PingYou Ltd’s, of Ostashev’s n = 303 packing (T-186) is now this case’s house: its exact certificate proves $s(303)\le 17.90995829106990799$$s(303)\le 17.90995829106990799$, the reported and the verified upper bound, rounded outward from its exact side. The exact certificate side improves the previous verified exact side by about 1.79×10−19$1.79\times {10}^{-19}$. The earlier ceiling, displayed outward as $17.9099582910699080$$17.9099582910699080$ from Ostashev’s packing (T-162), applied until this adoption and stays retained as history (the certificate).

House adoption, 15 October 2026. Ostashev’s packing (T-162) was this case’s house until 16 October 2026: its exact certificate proves $s(303)\le 17.9099582910699080$$s(303)\le 17.9099582910699080$, the reported and the verified upper bound, 3.11×10−3$3.11\times {10}^{-3}$ below the ceiling the case held until then, $17.9130654627385324$$17.9130654627385324$ from Chaoweeraprasit’s packing, improved by Daniel (T-146), which stays retained as history (the certificate).

House adoption, 11 October 2026. Daniel’s display regularization of Chaoweeraprasit’s SQUISH packing (T-146) was this case’s house until 15 October 2026: its exact certificate proves $s(303)\le 17.9130654627385324$$s(303)\le 17.9130654627385324$, the reported and the verified upper bound, 7.25×10−3$7.25\times {10}^{-3}$ below the ceiling the case held until then, $17.9203123729203498$$17.9203123729203498$ from Chaoweeraprasit’s packing (T-113), which stays retained as history (the certificate).

The Upper Bound

Chaoweeraprasit (itsnaka), using SQUISH, reports s(303)≤Sn​$s(303)\le S_n$, with Sn​=703687441776641261029876953859​$S_n=\frac{1261029876953859}{70368744177664}$ in SQUISH’s ten-packing release. The certificate gives rational centres and half-angle parameters for 303 unit squares. The source’s original finite decimal display is $17.9203123729203497$$17.9203123729203497$; the rational fraction states the claimed bound exactly.

The new packing improves the earlier reported side $17.924341009851128373110514612828$$17.924341009851128373110514612828$ from [evand exact optima 2026-10-05]. This repository confirmed the upper bound by independently re-implemented exact-rational checks: native exact_verify and devtools.check_rational_witness_independent accept every pair and wall of the new packing and reject both geometric controls. The verified display is $17.9203123729203498$$17.9203123729203498$, the exact source side rounded upward at sixteen decimals. Both accepted reviews cover the shared half-angle conversion and the complete roster. The submitted certificates establish feasible upper bounds and make no optimality or rigidity claim. Separately, this repository’s numerical translation screen finds a nontrivial feasible motion in the retained configuration. That numerical assessment concerns this configuration alone; it does not settle the optimum or all packings at this side.

The author credits Ellsworth’s records and tools and states that SQUISH’s solver, verification and issue were written with Claude Opus 5.5 under his direction, management, review and steering. The source packet retains derived packing facts and source metadata.

Earlier Packing

Couzo found the earlier packing; Daniel improved it. Its reported side was $17.924341009851128373110514612828$$17.924341009851128373110514612828$. The earlier certified ceiling $17.924341009851128373110514612828$$17.924341009851128373110514612828$ was the verified upper bound before the SQUISH certificate (T-098), supported by Daniel’s certificate packet. This repository replayed Daniel’s two source checkers and independently decided the rational certificate with its own exact-rational routes; the packet records the shared premises and receipts. Any optimality or rigidity observations about that packing concern its own pose.

The lower bound

The strongest lower bound independently verified in this record is Karakuş’s general bound, which applies to every nonsquare $N\ge 8$$N\ge 8$:

Correction, 2 October 2026. Until that date the verified lower bound here was Nagamochi’s general closed form, s(N)≥min(⌈N​⌉,N−2⌊N​⌋+1​+1)$s(N)\ge min(\lceil \sqrt{N}\rceil ,\sqrt{N-2\lfloor \sqrt{N}\rfloor +1}+1)$, which is stronger at this $n$$n$ and is now recorded as a reported bound. Its published proof rests on Nagamochi’s Lemma 1, which Karakuş showed false; nothing is disproved, and no packing beating it is known (review of 2 October 2026). This register had recorded that proof as verified, its own error, logged as defect D-516.

Source-reported bounds are recorded separately from this independently verified theorem.

Verification Code

The programs behind this case’s verified bounds, by their evidence. The code column says how the code that ran stands to the code its producer used. VERIFIERS.md says what each program is and whose it is.

Evan Daniel’s certificate (T-146)

Daniel’s display regularization of Chaoweeraprasit’s SQUISH packing, reported in his regularized record lists, on no issue, at exact side $8956532731369266152919876895603/500000000000000000000000000000$$8956532731369266152919876895603/500000000000000000000000000000$, displayed upward as $17.9130654627385324$$17.9130654627385324$ (T-146). The certificate gives a rational side and, for each of the 303 unit squares, a rational centre and the tangent of its half-angle; the retained packet holds it with the complete native jobs that decided it.

Both maintained exact routes decided it here, sqpack’s exact separating-axis verifier and the independent rational corner checker, with its duplicate-square and outside-container controls, and a third exact route, half-extent containment and exact intersection area, decided it again. No route here is the source’s code, so the replay is independently re-implemented. The review of 11 October 2026 and the final review of 11 October 2026 accepted the replay for finite feasibility. That proves $s(303)\le 17.9130654627385324$$s(303)\le 17.9130654627385324$, the verified upper bound until 15 October 2026: confirmed, independently re-implemented. It says nothing about optimality, rigidity or a local minimum.

The certificate regularizes for display the packing T-136 records, at the side the source reports as that packing’s exact optimum, so the packing stays with its finder and Daniel is credited with the regularization and the certificate. That the two are one packing is the source’s claim, measured here and not decided (T-146’s regularizations).

The source’s credits say the repository’s work was produced by Claude (Anthropic) under human direction.

The house it replaces, $17.9203123729203498$$17.9203123729203498$ from Chaoweeraprasit’s packing (T-113), stays retained with its own replay as history. The other certificates confirmed here at this count, T-136 at $17.9130654627385328$$17.9130654627385328$, T-134 at $17.9174439254942359$$17.9174439254942359$ and T-138 at $17.920312372919$$17.920312372919$, stay verified and are not selected.

Daniil Ostashev’s certificate (T-162)

Ostashev’s packing, reported on jlevy/squares#562, at an exact rational side, displayed upward as $17.9099582910699080$$17.9099582910699080$ (T-162). The certificate gives a rational side and, for each of the 303 unit squares, a rational centre and the tangent of its half-angle; the retained packet holds it with the complete native jobs that decided it.

Both maintained exact routes decided it here, sqpack’s exact separating-axis verifier and the independent rational corner checker, with its duplicate-square and outside-container controls, and a third exact route, half-extent containment and exact intersection area, decided it again. No route here is the source’s code, so the replay is independently re-implemented. The review of 14 October 2026 accepted the replay for finite feasibility. That proves $s(303)\le 17.9099582910699080$$s(303)\le 17.9099582910699080$, the verified upper bound until 16 October 2026: confirmed, independently re-implemented. It says nothing about optimality, rigidity or a local minimum.

The issue says the author drives an AI-assisted research loop with his own ideas, the rectangle library and the composition being his, and that AI agents wrote and ran the search, composition and verification code.

The issue says the 129 is cut from the n = 302 house of the time, Daniel’s view of Chaoweeraprasit’s SQUISH packing, and re-optimised, and that the 204 and 303 are new arrangements. Measured here, the 129 pairs square for square with neither Xu’s packing nor T-146’s, though 46 of Xu’s squares lie in place under a quarter turn, and 49 of the 302’s reappear in it by pose; that supports the author’s account and establishes none of it.

The house it replaces, $17.9130654627385324$$17.9130654627385324$ from Chaoweeraprasit’s packing, improved by Daniel (T-146), stays retained with its own replay as history. The other certificates confirmed here at this count, T-136 at $17.9130654627385328$$17.9130654627385328$, T-134 at $17.9174439254942359$$17.9174439254942359$, T-138 at $17.920312372919$$17.920312372919$ and T-113 at $17.9203123729203498$$17.9203123729203498$, stay verified and are not selected. T-174 at $17.9099582910699080$$17.9099582910699080$, 1.79×10−19$1.79\times {10}^{-19}$ below this house, is confirmed here and accepted by the review of 14 October 2026. From 15 October 2026 until the owner’s house rule of 16 October 2026 lifted the hold, PR #574’s houses were held for the owner, since their witnesses would add about 18.5 MB to a checkout and their custody inputs about 5.8 MB to every worker’s snapshot.

Mykhailo Polkovskyi’s certificate (T-186)

Polkovskyi’s tighter certificate, after PingYou Ltd’s, of Ostashev’s n = 303 packing, reported in his repository on 14 October 2026, with no issue, at an exact rational side, displayed upward as $17.90995829106990799$$17.90995829106990799$ (T-186). The certificate gives a rational side and, for each of the 303 unit squares, a rational centre and the tangent of its half-angle; the retained packet holds it with the complete native jobs that decided it.

Both maintained exact routes decided it here, sqpack’s exact separating-axis verifier and the independent rational corner checker, with its duplicate-square and outside-container controls, and a third exact route, half-extent containment and exact intersection area, decided it again. No route here is the source’s code, so the replay is independently re-implemented. The review of 16 October 2026 accepted the replay for finite feasibility. That proves $s(303)\le 17.90995829106990799$$s(303)\le 17.90995829106990799$, the verified upper bound: confirmed, independently re-implemented. It says nothing about optimality, rigidity or a local minimum.

The certificate is Polkovskyi’s tightening of the packing T-174 records, measured here pose by pose as that packing (T-186’s regularizations), so the packing keeps its finder’s credit and Polkovskyi is credited with the certificate.

The commit makes no statement about AI assistance; the author’s issue 593 discloses Gemini assistance with solver scripting, precision checks and formatting.

The house it replaces, $17.9099582910699080$$17.9099582910699080$ from Ostashev’s packing (T-162), stays retained with its own replay as history. The other certificates confirmed here at this count, T-174 at $17.9099582910699080$$17.9099582910699080$, T-146 at $17.9130654627385324$$17.9130654627385324$, T-136 at $17.9130654627385328$$17.9130654627385328$, T-134 at $17.9174439254942359$$17.9174439254942359$, T-138 at $17.920312372919$$17.920312372919$ and T-113 at $17.9203123729203498$$17.9203123729203498$, stay verified and are not selected.