Planar Graph Theory and the Four Color Problem (Ⅱ)——Five Color Theorem and Formulation of Four color Problem

Abstract:

      This is the second part of the series of five papers about planar graph theory and the four color problem.It contains the following five sections: §6 Related to the Euler formulal§7 Kempe chains and the five color theorem; §8 Color functions; §9Fundamental formulation of the four color problem; §10 Cubic planar graphs;