SilverSight/.openresearch/artifacts/hn_spectral_database_eval.md
openresearch 4141597e89 feat: experiment results — HN spectral database + q-profile sweep
Adds measured results from two CPU runs:

1. HN spectral database (run 019f2c52):
   Hoffman bound on 6 graphs. Tight for regular (path, cycle, complete),
   gap=1 for unit-distance (Moser spindle, Golomb graph). Pattern
   suggests spectral detection loses exactly 1 color for unit-distance graphs.

2. q-profile sweep (run 019f2d9c):
   Sweeps q = L₁/L₀ over coprime fractions. REFUTES the prediction
   that q < 1 (poloidal-dominated) is Sidon-favorable: q > 1 has
   100% Sidon rate vs 40-60% for q < 1. The toroidal/poloidal analogy
   doesn't directly control Sidon-ness via the q-ratio direction.

   For non-Sidon label sets: 0% Sidon at ALL q values (q-profile
   cannot CREATE Sidon from non-Sidon, only PRESERVE it).

All scripts, formal modules, and docs already committed to main.
This commit adds the experiment artifact JSONs and EVALs.
2026-07-04 14:57:46 +00:00

1.5 KiB

Hadwiger-Nelson Spectral Database

Date: 2026-07-04T08:50:51Z SHA-256: 6af248bdf51d4a90b6e286e4decc33f60b153b4b162c677ecfbaf9f12b20641c Includes de Grey: False

Spectral Bounds Comparison

Graph n e λ_max λ_min Hoffman χ_Hoff Welch-Wynn χ_WW Known χ Gap
Moser spindle 7 12 3.6458 -2.0000 2.8229 3 N/A None 4 gap=1
Golomb graph (8 vertices, 10 edges) 8 10 2.6813 -2.3234 2.1541 3 N/A None 4 gap=1
Empty graph (10v baseline) 10 0 0.0000 0.0000 inf None N/A None 1 ?
Path graph P10 (baseline) 10 9 1.9190 -1.9190 2.0000 2 N/A None 2 tight
Cycle C5 (baseline) 5 5 2.0000 -1.6180 2.2361 3 N/A None 3 tight
Complete K4 (baseline) 4 6 3.0000 -1.0000 4.0000 4 N/A None 4 tight

Key Findings

  1. Hoffman bound (χ ≥ 1 - λ_max/λ_min): classic spectral bound
  2. Welch-Wynn bound (χ ≥ n/(n - λ_max)): another spectral bound
  3. Gap: difference between best spectral bound and known chromatic number
    • 'tight' = spectral bound matches known χ
    • 'gap=N' = spectral bound is N below known χ

The gap measures how much chromatic information is NOT captured by the spectrum. For the octagon principle, a tight spectral bound means the nonlinear property (colorability) IS detectable from the linear invariant (eigenvalue spectrum).