1Asst. Professor,
2Asst. Professor,
In this paper, we consider 3-colorable planar graphs. The Four Color Theorem (4CT) gives an O(n2) time algorithm to 4-color any planar graph. Graph coloring for 3-colorable graphs receives very much attention by many researchers in theoretical computer science. Deciding 3-colorablility of a graph is a well-known NPcomplete problem. We give a very simple O (n2) time algorithm to 4-color 3-colorable planar graphs.
The Four color Theorem, 3-colorable graph