didericis
6c7bd9e0db
For G_0 a minimum-order 5-chromatic maximal planar graph and any 4-coloring of G_0 - uv, the endpoints u, v must share a color, and the color classes pairing that color with each of two other colors must each induce a u-v path. The Kempe-chain parts follow from a standard swap-on-component contradiction against the shared-color claim. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>