The four color theorem is a theorem of mathematics.It says that in any plane surface with regions in it (people think of them as maps), the regions can be colored with no more than four colors.Two regions that have a common border must not get the same color. They are called adjacent (next to each other) if they share a segment of the border, not just a point. The Four Color Problem dates back to 1852 when Francis Guthrie, while trying to color the map of counties of England noticed that four colors sufficed. He asked his brother Frederick if it was true that any map can be colored using four colors in such a way that adjacent regions (i.e. Concerning the problem itself, $4$ is a right answer because of the four color theorem (every planar graph has chromatic number at most $4$). The Four-Color Problem: Concept and Solution Steven G. Krantz October 14, 2007 ... Concept and Solution. Unlike computer science or biology, where the concept of truth is in a constant state ... four-color problem. Prologue Modern mathematics is a rich and complex tapestry of ideas that have evolved over thousands of years.