Three Sufficient Conditions for Planar Graphs to be 3-Colorable
Xie De-zheng · Journal of Henan Normal University · 2011
A planar graph is 3-colorable if its vertices can be colored with three colors,no two adjacent vertices coloring the same color.It has studied that planar graphs which can be 3-colorable provided that the cycles of length at most 6 or 7 which satisfy some conditions.