What Columbia University professor proved the Earle-Hamilton fixed-point theorem with Clifford Earle in 1968?
Earle–Hamilton fixed-point theorem:  The result was proved in 1968 by Clifford Earle and Richard S. Hamilton by showing that, with respect to the Carathéodory metric on the domain, the holomorphic mapping becomes a contraction mapping to which the Banach fixed-point theorem can be applied. Richard S. Hamilton: Richard Streit Hamilton (born 1943) is Davies Professor of Mathematics at Columbia University.
Richard S. Hamilton