Joseph Ritt

Joseph Fels Ritt was an American mathematician at Columbia University, born in New York City on 23 August 1893 and died on 5 January 1951. He is best known for his work on the theory of differential equations from the algebraic viewpoint, which he called differential algebra, and which was developed further by him and his student Ellis Kolchin. After starting at City College of New York he took a B.A. at George Washington University in 1913 and a doctorate at Columbia in 1917 under the supervision of Edward Kasner. He joined the Columbia faculty in 1921, chaired the department from 1942 to 1945 and became Davies Professor of Mathematics in 1945. He was elected to the United States National Academy of Sciences in 1933, spoke at the International Congress of Mathematicians in 1924 and 1950, and is known for characterizing integrals that can be solved in closed form, for beginning the study of differential algebraic groups and for the method of characteristic sets.