Nathan Mendelsohn

Nathan Saul Mendelsohn ( born April 14, 1917 in Brooklyn, † July 4, 2006 in Toronto ) was a Canadian mathematician, professor at the University of Manitoba. He dealt with group theory, geometry and combinatorics.

Mendelsohn moved with his parents ( Jewish immigrants from Romania and Galicia ) in 1918 to Toronto, where he studied mathematics and received his doctorate in 1941 with Richard Brauer and Gilbert de Beauregard Robinson (A Group - Theoretic Characterization of the General Projective collineation group). As a student he participated successfully in the 1938 Putnam competition part (another team member at the University of Toronto was Irving Kaplansky ). During World War II he worked as a cryptologist. In 1945 he became a professor at Queen's University in Kingston and in 1947 at the University of Manitoba, where he remained until his retirement in 2005. In the early 1960s he also worked for the Rand Corporation.

The Dulmage - Mendelsohn decomposition to generate maximum matchings of bipartite graphs is named after him. It has applications in mesh generation in finite elements. It addressed, among others, Steiner triple systems and their generalizations, orthogonal Latin squares, block diagrams, quasi groups and groupoids. For a work with Diane Johnson and AL Dulmage of 1961 ( Orthomorphisms of groups and orthogonal latin squares, Canad. J. Math, Volume 13, 1961, pp. 356-372 ), he received the Tory Medal of the Royal Society of Canada. In it, they constructed five mutually orthogonal Latin squares and arrived ( so the eulogy 1979) closer than anyone else composite to the solution of the problem of the construction of a projective plane of order. His application of algebraic techniques in combinatorics and conversely from combinatorics in algebra resulted in justification of its own branch of combinatorics ( combinatorial universal algebra).

1969 and 1971 he was President of the Canadian Mathematical Society. He was a Fellow of the Royal Society of Canada (1957 ), the Henry Marshall Tory Medal he received in 1979. In 1999 he received the Order of Canada and in 1975 Jeffery -Williams Prize.

In the early 1950s he was also an award-winning amateur magician, especially with card tricks ( and also published on mathematics of card tricks ). He was married and had two sons, of whom Eric Mendelsohn professor of mathematics at the University of Toronto was.