didericis 6c7bd9e0db Add Kempe-chain structure of 4-colorings of edge-deletion subgraphs ...

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>

2026-05-14 00:31:40 -04:00

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