T-252: s(44)=7, by a closed mixed cover of points and grid-line segments

V3 C3 Optimality confirmed

2026-10-26 published · Khalili, Gharabaghi after Daniel · n=44

s(44)=7: the lower half by Mohsen Khalili and Sara Gharabaghi's closed mixed cover of 26 October 2026, the upper half by the 7×7 grid. It is the case k = 7 of the k^2 - 5 series, after T-066 (k = 8), T-184 (k = 9) and T-191 (k = 10).

The cover is 15,525 weighted points of [0,7]^2 and 3,912 segments of length 1/50 on the lines x, y in {1, ..., 6}, each carrying its mass uniformly by length, total 2199755099/50000000 = 43.99510198 < 44, D4-invariant, in Daniel's mixed format. Every closed unit square in [0,7]^2 captures mass at least one, so a packing of 44 at side below 7, scaled up to side 7, would capture at least 44.

The source reports the cover accepted by Daniel's zmx2, with outward-rounded binary64 enclosures and exact integer mass tests, over all 4,900 D4 roots and all 39,200 unreduced roots, none uncertified, and by his exact-rational zm_mixed.py over all 9,800 D4 roots at depth 24 with its 27 open roots closed at depth 30.

Both zmx2 sweeps were replayed here in full from the bytes the source pins, every root's census equal to the source's log, and two mutated covers were refused: s(44)≥7 is confirmed, reproduced with the producer's code. Two reviews of 31 October found no mathematical defect, one of them by a separately prompted lane with no context shared with the import lane, which also replayed the D4 sweep and ran controls of its own.

Mohsen Khalili and Sara Gharabaghi, s44-equals-7, building on Daniel's closed mixed covers, format, checkers and s(45)=7 cover. Registration was requested in jlevy/squares#842. The source says the search, the certificate, the separation tool and the verification runs were produced with Claude (Anthropic) under the authors' direction.

Significance, composition and next rung
Significance
An exact value for a case that was open, by Daniel's method at a new count, as T-066 settled s(59)=8: a substantive case result, not a new technique or a family. Each instance of the k^2 - 5 series is its own linear-programming solve, and the source's separation step for near-axis wall valleys is a search method, not part of the proof. The independent 31 October review confirmed the draft.
Composition
Compound, and the minimum is set by the lower half: E-khalili-842-cover-replay (interval-certified, zmx2 replayed here over the unreduced pose space and the D4 region), the upper half the grid (E-basic-grid-upper, exact-algebraic). The deciding checker is Daniel's, which also decides T-053, T-062 and T-066. The source's zm_mixed.py records are read, not replayed, and are not recorded as evidence.
Next rung
V4 and C4 need a human oversight record. Two adversarial AI reviews by distinct reviewers are retained: one written in the import lane's context, and one by a separately prompted lane that shared none of it. V5 needs the covering statement proved in a proof assistant and an expert formalization review. zm_mixed.py's complete pass, about 138 CPU-hours by the source's records (think-qvp6), would be a second machine method by the producer and raises no rung.
Unfinished confirmations
C4: a human oversight record that checks the trust boundary, the certificate's meaning and the AI review's findings. Not priced.
Novelty
previously-published Present in an identified source

The case

Case record

n=44

7
678
6.6337.633
nn+1

Proven

s(44)=7

  • optimal
  • exact

Citation record n-044

lowerKhalili, Gharabaghi after Daniel 2026, GitHub (confirmed T-252)

The case record

LowerUpper
Verified77
Reported77
Gap0 solved: the verified bounds meet

Results on the case

13 results in the register on n=44, 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) for 4≤n≤324

    V0 C1 Lower bound incomplete on this case, superseded by T-252

    Nagamochi · Nagamochi 2005 · source · register

  2. 2026-09-04 published T-085

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

    V3 C3 Correction confirmed

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

  3. 2026-09-27 published T-046

    Rectangle-density lower bounds verified at 48 counts in n=18…95

    V3 C3 Lower bound confirmed superseded by T-252

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

  4. 2026-09-28 published T-070

    Rectangle-density lower bounds replayed at 25 counts in n=29…95

    V3 C3 Lower bound confirmed superseded by T-252

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

  5. 2026-09-29 published T-058

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

    V3 C3 Method limit confirmed

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

  6. 2026-09-29 published T-083

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

    V3 C3 Lower bound confirmed on this case, superseded by T-252

    Karakuş · Karakuş 2026 · source · register

  7. 2026-10-01 published T-068

    Rectangle-density lower bounds verified at 34 counts in n=19…95

    V3 C3 Lower bound confirmed on this case, superseded by T-252

    Hosono after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 rectangle bounds 2026-10-01 · packet · source · review · register

  8. 2026-10-01 published T-074

    Rectangle-density lower bounds replayed at 31 counts in n=19…95

    V3 C3 Lower bound confirmed on this case, superseded by T-252

    Hosono after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 rectangle bounds 2026-10-01 · packet · packet · source · review · register

  9. 2026-10-04 published T-090

    Mixed rectangle-measure lower bounds verified at 17 counts in n=42…96

    V3 C3 Lower bound confirmed on this case, superseded by T-252

    Hosono after Tokoharu, Levy, Stromquist, Nagamochi, Burns, Massaccesi · wand125 mixed bounds 2026-10-04 · packet · source · review · register

  10. 2026-10-07 published T-124

    Reported non-strict local minima for 178 source configurations

    V0 C0 Restricted optimality recorded

    Daniel after Couzo · Daniel exact and local reports 2026 · packet · register

  11. 2026-10-12 published T-261

    Reported grade-C local minima for 233 source configurations of field degree at most 4

    V3 C1 Restricted optimality incomplete

    Daniel after Schadt, Ellsworth, Levy · Daniel exact and local reports 2026-10-12 · packet · packet · register

  12. 2026-10-13 published T-177

    Mixed rectangle-measure lower bound s(44)≥2799/400 reported, on a 2,073-direction declared net

    V0 C1 Lower bound reviewed superseded by T-252

    Hosono after Tokoharu and Levy · wand125 fine-net n37 n39 n44 2026-10-13 · packet · register

  13. 2026-10-26 published T-252 this result

    s(44)=7, by a closed mixed cover of points and grid-line segments

    V3 C3 Optimality confirmed

    Khalili, Gharabaghi after Daniel · Khalili Gharabaghi s44 cover 2026-10-29 · packet · source · review · register