  In this paper, two recursion formulae of chromatic polynomial of a maximal
planar graph G are obtained. Moreover, the application of these formulaes to
the proof of Four-Color Conjecture is investigated. By using these formulae,
the proof of Four-Color Conjecture boils down to the study on a special class
of graphs, viz., 4-chromatic-funnel pseudo uniquely-4-colorable maximal planar
graphs.
