Hans Zassenhaus

Hans Zassenhaus (1912 to 1991) was a German mathematician known for work in many parts of abstract algebra and as a pioneer of computer algebra. Born in Koblenz, he grew up in Hamburg, where he studied under Emil Artin and took his doctorate in 1934 with a thesis on doubly transitive permutation groups, now called Zassenhaus groups, which have had a deep impact on the classification of finite simple groups. While still a student he proved the butterfly lemma, a refinement of normal chains that is also named after him, and he wrote the textbook Lehrbuch der Gruppentheorie, later translated as Theory of Groups. After the Second World War he joined McGill University, where he supervised Joachim Lambek, then taught at the University of Notre Dame and, from 1965 until his retirement in 1982, at Ohio State University. He served as editor in chief of the Journal of Number Theory from its first issue in 1967.