H. J. Ryser

Herbert John Ryser ( born July 28, 1923 in Milwaukee, † 12 July 1985 in Pasadena ) was an American mathematician who worked on combinatorics.

Ryser graduated from the University of Wisconsin (Bachelor in 1945, Master 1947), where he received his doctorate in CJ Everett and Cyrus MacDuffee 1948 ( " Rational Vector Spaces" ). 1948/9 he was at the Institute for Advanced Study. In 1949 he became Assistant Professor, 1952 Associate Professor and in 1955 Professor at the Ohio State University, as well as simultaneously Marshall Hall. In 1962 he became a professor at Syracuse University and in 1967 at Caltech.

In 1949 he proved with Richard Bruck ("The non existence of finite projective planes Certain, Canadian Journal of Mathematics vol.1, 1949, p.88 -92) n the set of Bruck- Ryser- Chowla about possible atomic numbers of finite projective planes ( 1950 extended from him and Sarvadaman Chowla to other symmetric block diagrams). That remained to this day the only general theorem of non-existence of certain finite projective planes. In 1982 he gave a simpler proof of the theorem ("The existence of symmetric block designs", Journal of Combinatorial Theory, Bd.32, p.103 ), such as at the same time Hanfried Lenz.

In 1970 he was invited speaker at the International Congress of Mathematicians in Nice (New types of combinatorial designs) and 1962 in Stockholm (The width of a ( 0,1) matrix, with DR Fulkerson ).

Writings

• Combinatorial Mathematics, Carus Mathematical Monographs 1963