The unrestricted census suggested flip-symmetry already excludes a
vanishing fraction of maximal planar graphs; this commit re-runs the
same enumeration over the minimum-degree-5 subclass (where any
minimum-order 5-chromatic counterexample must live) to check whether
the restriction tightens the bound. It does not: the density decays
to zero there as well, only at a gentler geometric rate (~0.63 per
step instead of ~0.5).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
