H. S. M. Coxeter

H.S.M. Coxeter is widely recognized for his significant contributions to the field of geometry, particularly his work on regular polytopes and his influence on modern geometric thought. He is considered one of the most important geometers of the 20th century.

Yes, H.S.M. Coxeter collaborated with several other mathematicians throughout his career, notably with W.O.J. Moser on "Generators and Relations for Discrete Groups" and with S.L. Greitzer on "Geometry Revisited."

The Coxeter group is a fundamental concept in mathematics, named after H.S.M. Coxeter, which describes a group generated by reflections. This concept has applications in various areas of mathematics, including geometry, algebra, and combinatorics.