n = 100 provedO=R

s(100)=10

The best packing known for 100 squares, side 10,
10
91011
nn+1

Proven

s(100)=10

  • optimal
  • exact
  • rigid

Bounds

Best known packing

10

Construction
grid
Tilt angles
0∘
Source
[Kingbird]
Evidence
E-kingbird-upper-register
Verified upper bound

10

The reported value, verified here.

Evidence
E-basic-grid-upper
Reported lower bound

10

Kind
perfect square
Evidence
E-basic-area-lower
Verified lower bound

10

The reported value, verified here.

Evidence
E-basic-area-lower
Gap

0

Solved: the verified bounds meet.

Results in the register

Verification

upper: replayed here; lower: replayed here

—

Rigidity

locally rigid, verified, exact algebraic

Evidence: E-perfect-square-tiling-rigid

Scope

This record's side is verified above and below at exactly 10, so its 100 unit squares of total area 100 sit in a 10 by 10 container of area 100. The packing is a tiling with no slack anywhere, so no square admits any feasible motion. This is global rather than local, and holds for the exact configuration rather than for a materialized approximation of it. It says nothing about s(n) beyond what the tiling itself shows.

Evidence and sources
4 evidence entries

E-kingbird-upper-register, E-basic-area-lower, E-basic-grid-upper, E-nagamochi-lower

s(100) — solved

s(100)=10, trivially: 100=102, so the grid is optimal and the area bound n is already tight.

Corrected 4 October 2026: the verified lower bound cites the area bound, E-basic-area-lower; until 2 October it cited Nagamochi 2005 (E-nagamochi-lower) at the same value, whose Lemma 1 is false (D-516).

The edge of this corpus

This artifact is the last in the frontier corpus, which covers n≤100 to match the range of Friedman’s survey. The record catalogue itself goes considerably further — all n≤324, plus selected larger cases at 626,1453,1765,1850 and 2043 — and the algebraic degrees out there are what make exact verification interesting: degree 40 at s(300), degree 62 at s(1453).

Extending this corpus past 100 is mechanical for the structured fields and would be worth doing alongside the machine-readable record parser described in the research document’s program. The editorial content is the part that does not automate.

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-basic-area-lower replayed here independent V-check-basic-bounds (first-party)
verified upper E-basic-grid-upper replayed here independent V-check-basic-bounds (first-party)