n = 22 provedO=

s(22)=5

The best packing known for 22 squares, side 5, Wolfram Bentz 2018
5
456
4.6905.690
nn+1

Proven

s(22)=5

  • optimal
  • exact

Citation record n-022

lowerBentz 2016, arXiv:1606.03746

Bounds

Best known packing

5

Found by
Wolfram Bentz 2018
Construction
hand
Source
[Kingbird]
Evidence
E-kingbird-upper-register
Verified upper bound

5

The reported value, verified here.

Evidence
E-basic-grid-upper
Reported lower bound

5

Proved by
Wolfram Bentz 2016
Kind
unavoidable points
Source
[Bentz 2016]
Evidence
E-bentz-2016-proof
Verified lower bound

5

The reported value, verified here.

Evidence
E-bentz-2016-proof
Gap

0

Solved: the verified bounds meet.

Results in the register

Verification

upper: replayed here; lower: external proof (not read here)

—

Rigidity

not rigid, numerically checked, numerical multiprecision

Evidence: E-translation-escape-not-rigid

Scope

Square 17 of the retained witness (witness id 18) translates 1 along (0, 1) with the packing still valid, so the configuration admits a non-trivial feasible motion; 4 of its 22 squares do. Every constraint is exactly affine in the slide parameter, so the arithmetic carries no linearization error, but the coordinates are the witness's own finite-precision transcription: this settles the retained configuration, not the true optimum. Rigidity and optimality are independent, and this bears only on the former.

Evidence and sources
4 evidence entries

E-kingbird-upper-register, E-basic-grid-upper, E-nagamochi-lower, E-bentz-2016-proof

s(22) — solved

s(22)=5, proved by Wolfram Bentz (arXiv 2016; the catalogue dates the proof to October 2018), together with s(33)=6. When this record was first written, on 22 August 2026, these were the most recent new exact values of s(n) proved for any non-trivial case, and the lower-bound frontier had not moved since. It has moved many times since then; STATUS.md lists every case solved now. The verified lower bound rests on Bentz’s proof alone: nobody here has worked through it, and no second route to s(22)=5 has been replayed here.

What the paper contributes beyond two values

The 2016 paper is where the field’s own name for its method appears in print. Bentz states it plainly: optimality proofs for square packing use arguments based on resource starvation — subsets of the container are associated with numerical resources such that each packed box must consume a quantum, and the total available limits how many boxes fit.

That is the correct level of generality, and it organizes the entire lower-bound inventory as one idea being progressively de-discretised: points worth 1, points with a slider, segments measured by intersection length, weighted combinations, and finally the continuously varying families this paper introduces.

The open methodological question it raises

Bentz’s families reach an integer target (5). Whether the same machinery can reach an irrational target of high degree — which is what n=11 would require — is, as far as this research found, untested. That question is the most useful single thing to know about the state of the lower-bound art, and it gates n=11.

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.

bound evidence run code programs
verified lower E-bentz-2016-proof a published proof no code no verification code
verified upper E-basic-grid-upper replayed here independent V-check-basic-bounds (first-party)