彩色多項式と彩色数 : 閉路 C_5, C_6 の場合 Graph : 0 1 0 0 1 1 0 1 0 0 0 1 0 1 0 0 0 1 0 1 1 0 0 1 0 Chromatic Polynomial : X^5 - 5 X^4 + 10 X^3 - 10 X^2 + 4 X = (X) (X - 1) (X - 2) (X^2 - 2 X + 2) Chromatic Number = 3 -------------------------------------------- Graph : 0 1 0 0 0 1 1 0 1 0 0 0 0 1 0 1 0 0 0 0 1 0 1 0 0 0 0 1 0 1 1 0 0 0 1 0 Chromatic Polynomial : X^6 - 6 X^5 + 15 X^4 - 20 X^3 + 15 X^2 - 5 X = (X) (X - 1) (X^4 - 5 X^3 + 10 X^2 - 10 X + 5) Chromatic Number = 2