What Columbia University professor proved the Earle-Hamilton fixed-point theorem with Clifford Earle in 1968?
Richard S. Hamilton Richard Streit Hamilton (born 1943) is Davies Professor of Mathematics at Columbia University.
Birkhoff–Kellogg invariant-direction theorem In functional analysis, the Birkhoff–Kellogg invariant-direction theorem, named after G. D. Birkhoff and O. D. Kellogg, is a generalization of the Brouwer fixed-point theorem. The theorem states that: