The four-color theorem states, ``four colors at most, are required to color the regions of any map so that no two adjacent regions have the same color.''
This theorem was proved using a computer in 1976 by Kenneth Appel and Wolfgang Haken.
Before that, there was an idea using Kempe chains, which was published by Alfred Kempe in 1879.
However, a counterexample to this idea was found by Percy John Heawood in 1890.
In this article, I present a new direction for considering Kempe chains used by Alfred Kempe.
To reduce the number of colors of adjacent countries using Kempe's method, I will introduce a new coloring method and give a conjecture toward the proof of the theorem.
Research papers (publications of university or research institution)
