chromatic polynomial
英[krəʊˈmætɪk ˌpɔliˈnəumjəl]美[kroˈmætɪk ˌpɑliˈnomiəl]
The chromatic polynomial is a polynomial studied in algebraic graph theory, a branch of mathematics. It counts the number of graph colorings as a function of the number of colors and was originally defined by George David Birkhoff to attack the four color problem.