Heinz Hopf

lived from 1894 to 1971

Hopf's work was in algebraic topology. He studied vector fields and extended Lefschetz's fixed point formula. He also studied homotopy classes and defined what is now known as the 'Hopf invariant'.

Find out more at:
http://www-history.mcs.st-andrews.ac.uk/Mathematicians/Hopf.html