SilverSight/.openresearch/artifacts/EVAL.md
allaun 83b4f0ce2c feat: Direction B Gerver sofa implementation + CRTSidonN partial fix
Direction B results: Gerver sofa at T=100 produces χ=2 (bipartite),
not reaching χ≥4. Confirms 'unit-distance events are measure-zero.'

CRTSidonN: auto-generated, ~10 remaining structural issues. Design is
correct (natural n-moduli extension of CRT Sidon theorem).
2026-07-04 11:04:14 -05:00

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# Direction B: Gerver Sofa as Sidon — Results
**Experiment:** direction_b_gerver_sidon
**Date:** 2026-07-04T16:02:16Z
**Seed:** 0
**SHA-256:** `bb46c7e33b824ceecc90c6f00838ea21efe04af8dc9ddca6c3fcfa45fffab841`
**Motion samples:** 100 (4× Direction A's 24)
**Motion type:** Gerver optimal cycloidal (cubic timing)
**Gerver sofa arcs:** 18 (exact from Gerver 1992)
**Shapes tested:** gerver_sofa, half_disc, hammersley, rectangle
**Chromatic method:** DSATUR + exact for ≤16 + 50 greedy restarts
**Tolerance band:** |d 1| < 1e5
## Key Question
Does the actual 18-arc Gerver sofa with CRT Sidon boundary points and
T=100 motion samples generate a denser conflict graph than Direction A's
simplified shapes? A conflict graph with χ 4 would confirm the
sofa coloring approach has real structure.
## Conflict Graph Statistics (T=100)
| Shape | n | q | Area | Edges | Max Deg | χ | S2D? |
|---------------|----|-------|--------|-------|---------|---|------|
| gerver_sofa | 13 | 0.500 | 2.5162 | 5 | 1 | 2 | Y |
| gerver_sofa | 13 | 0.750 | 2.5162 | 5 | 1 | 2 | Y |
| gerver_sofa | 13 | 1.000 | 2.5162 | 5 | 1 | 2 | Y |
| gerver_sofa | 13 | 1.333 | 2.5162 | 5 | 1 | 2 | Y |
| gerver_sofa | 13 | 2.000 | 2.5162 | 5 | 1 | 2 | Y |
| gerver_sofa | 21 | 0.500 | 2.7460 | 15 | 3 | 2 | Y |
| gerver_sofa | 21 | 0.750 | 2.7460 | 15 | 3 | 2 | Y |
| gerver_sofa | 21 | 1.000 | 2.7460 | 15 | 3 | 2 | Y |
| gerver_sofa | 21 | 1.333 | 2.7460 | 15 | 3 | 2 | Y |
| gerver_sofa | 21 | 2.000 | 2.7460 | 15 | 3 | 2 | Y |
| half_disc | 13 | 0.500 | 0.2184 | 6 | 2 | 2 | Y |
| half_disc | 13 | 0.750 | 0.2972 | 6 | 2 | 2 | Y |
| half_disc | 13 | 1.000 | 0.3882 | 7 | 1 | 2 | Y |
| half_disc | 13 | 1.333 | 0.5284 | 8 | 2 | 2 | Y |
| half_disc | 13 | 2.000 | 0.8735 | 9 | 2 | 2 | Y |
| half_disc | 21 | 0.500 | 0.2200 | 18 | 2 | 2 | Y |
| half_disc | 21 | 0.750 | 0.2994 | 19 | 3 | 2 | Y |
| half_disc | 21 | 1.000 | 0.3911 | 21 | 3 | 2 | Y |
| half_disc | 21 | 1.333 | 0.5323 | 17 | 3 | 2 | Y |
| half_disc | 21 | 2.000 | 0.8799 | 22 | 2 | 2 | Y |
| hammersley | 13 | 0.500 | 0.4493 | 4 | 1 | 2 | N |
| hammersley | 13 | 0.750 | 0.4639 | 5 | 2 | 2 | N |
| hammersley | 13 | 1.000 | 0.4888 | 9 | 2 | 2 | N |
| hammersley | 13 | 1.333 | 0.5380 | 5 | 1 | 2 | N |
| hammersley | 13 | 2.000 | 0.6913 | 11 | 2 | 2 | N |
| hammersley | 21 | 0.500 | 0.4750 | 20 | 2 | 2 | N |
| hammersley | 21 | 0.750 | 0.4818 | 14 | 2 | 2 | N |
| hammersley | 21 | 1.000 | 0.5008 | 8 | 2 | 2 | N |
| hammersley | 21 | 1.333 | 0.5452 | 15 | 2 | **3** | N |
| hammersley | 21 | 2.000 | 0.6992 | 20 | 3 | 2 | N |
| rectangle | 13 | 0.500 | 0.7594 | 11 | 2 | 2 | N |
| rectangle | 13 | 0.750 | 0.7973 | 15 | 2 | 2 | N |
| rectangle | 13 | 1.000 | 0.8100 | 12 | 2 | 2 | N |
| rectangle | 13 | 1.333 | 0.7875 | 8 | 2 | 2 | N |
| rectangle | 13 | 2.000 | 0.6075 | 5 | 1 | 2 | N |
| rectangle | 21 | 0.500 | 0.7594 | 21 | 3 | 2 | N |
| rectangle | 21 | 0.750 | 0.7973 | 31 | 3 | 2 | N |
| rectangle | 21 | 1.000 | 0.8100 | 20 | 3 | 2 | N |
| rectangle | 21 | 1.333 | 0.7875 | 29 | 2 | 2 | N |
| rectangle | 21 | 2.000 | 0.6075 | 16 | 3 | 2 | N |
## χ Stability Across q
| Shape | n | χ range | Stable? |
|---------------|----|---------|---------|
| gerver_sofa | 13 | 22 | Y |
| gerver_sofa | 21 | 22 | Y |
| half_disc | 13 | 22 | Y |
| half_disc | 21 | 22 | Y |
| hammersley | 13 | 22 | Y |
| hammersley | 21 | 23 | Δ=1 |
| rectangle | 13 | 22 | Y |
| rectangle | 21 | 22 | Y |
## Comparison: T=24 vs T=100 (Max Edges)
| Shape | n | T=24 edges | T=100 edges | Ratio |
|---------------|----|-----------|------------|-------|
| gerver_sofa | 13 | 1 | 5 | 5.0 |
| gerver_sofa | 21 | 1 | 15 | 15.0 |
| half_disc | 13 | 2 | 9 | 4.5 |
| half_disc | 21 | 2 | 22 | 11.0 |
| hammersley | 13 | 3 | 11 | 3.7 |
| hammersley | 21 | 3 | 20 | 6.7 |
| rectangle | 13 | 1 | 15 | 15.0 |
| rectangle | 21 | 2 | 31 | 15.5 |
At T=24 (Direction A), the Gerver-like shape produced 02 edges. At T=100, the
actual Gerver sofa produces 515 edges a 515× increase. The time resolution
is critical.
## Sidon Property Verification
| Shape | n | 1D Sidon | 2D Sidon |
|---------------|----|----------|----------|
| gerver_sofa | 13 | Y | Y |
| gerver_sofa | 21 | Y | Y |
| half_disc | 13 | Y | Y |
| half_disc | 21 | Y | Y |
| hammersley | 13 | Y | N |
| hammersley | 21 | Y | N |
| rectangle | 13 | Y | N |
| rectangle | 21 | Y | N |
Only the Gerver sofa and half-disc preserve the 2D Sidon property. hammersley
and rectangle do not, due to non-uniform boundary spacing that creates vector
sum collisions.
## Key Quantitative Results
1. **Edge count increases 415× at T=100** across all shapes compared to T=24.
2. **χ = 2 for 39/40 configurations**, χ = 3 for Hammersley (n=21, q=1.333).
3. **Gerver sofa χ is exactly 2** at all q-values and both n perfectly stable.
4. **2D Sidon property preserved** by the Gerver sofa and half-disc.
5. **χ ≥ 4 not achieved** the success threshold from the design doc.
## Verdict
Direction B partially succeeds: the Gerver sofa generates more conflict edges
than simpler shapes at T=100 (up to 15 edges vs ~1 for T=24). However, the
chromatic number remains χ 2 for the Gerver sofa (χ=2 everywhere). The one
χ=3 observation (Hammersley, n=21) is an outlier, not evidence of systematic
structure.
**The design doc's honest assessment was correct:** unit-distance events are
measure-zero in continuous space. Even with the Gerver sofa's wall-hugging
geometry and 4× higher time resolution, the conflict graph is essentially
bipartite. The failure mode matches Direction A: geometry does not produce
enough exact unit-distance coincidences.
**What the Gerver sofa does confirm:**
- The 18-arc construction with CRT Sidon boundary preserves the 2D Sidon property
(all pairwise vector sums distinct) this is non-trivial.
- The Gerver optimal motion generates more transient conflicts than the simple
translaterotatetranslate motion (515 edges vs 02).
- χ is stable across q for the Gerver sofa (χ=2 everywhere) this is a property
of the shape, not vertex ordering.
**What it does not confirm:**
- The octagon principle does NOT apply to sofa conflict graphs.
- The q-profile (toroidal/poloidal ratio) has minimal effect on χ.
- Upper bounds on χ (Hoffman, Welch-Wynn) are not useful when χ 2.
## Recommendation
The HN spectral database approach (already working) is the more promising path.
The gap=1 for Moser spindle and Golomb graph is a real, measured result.
Extend to more unit-distance graphs and look for the gap=1 pattern, rather than
pursuing sofa-based conflict graphs.