1932-

American mathematician known for his work in topology, the branch of mathematics that explores certain properties of geometric figures. In 1976 he solved the four-color problem, originally posed in 1850, that has enabled maps to be drawn and color-oriented so that no two adjacent regions are of the same color. He received his B.S. from Queens College (1953) and his Ph.D. in mathematics from the University of Michigan (1956). He later taught at the University of New Hampshire.