Herbert John Ryser (July 28, 1923 – July 12, 1985) was a professor of mathematics, widely regarded as one of the major figures in combinatorics in the 20th century.Ryser's biography
at the

Ohio State University The Ohio State University, commonly called Ohio State or OSU, is a public land-grant research university in Columbus, Ohio. A member of the University System of Ohio, it has been ranked by major institutional rankings among the best publ ...

website He is the namesake of the Bruck–Ryser–Chowla theorem, Ryser's formula for the

computation of the permanent of a matrix In linear algebra, the computation of the permanent of a matrix is a problem that is thought to be more difficult than the computation of the determinant of a matrix despite the apparent similarity of the definitions. The permanent is defined sim ...

, and

Ryser's conjecture In graph theory, Ryser's conjecture is a conjecture relating the maximum matching size and the minimum transversal size in hypergraphs. This conjecture first appeared in 1971 in the Ph.D. thesis of J. R. Henderson, whose advisor was Herbert John R ...

Early life

Ryser was born to the family of Fred G. and Edna (Huels) Ryser. He received the B.A. (1945), M.A. (1947), and Ph.D. (1948) from the

University of Wisconsin A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, ...

.Richard A. Brualdi: "In memoriam: Herbert J. Ryser", ''Journal of Combinatorial Theory, Series A'' 47(1) (January 1988), pp. 1–5 His doctoral thesis "Rational Vector Spaces" was supervised by Cornelius Joseph Everett, Jr. and Cyrus C. MacDuffee. (Ryser was Everett's only doctoral student.)

Career

After his Ph.D., Ryser spent a year at Princeton's

Institute for Advanced Study The Institute for Advanced Study (IAS), located in Princeton, New Jersey, in the United States, is an independent center for theoretical research and intellectual inquiry. It has served as the academic home of internationally preeminent schola ...

, then joined the faculty of

. In 1962 he took a professorship at Syracuse University, and in 1967 moved to

Caltech The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

. His doctoral students include Richard A. Brualdi, Clement W. H. Lam, and

Marion Tinsley Marion Franklin Tinsley (February 3, 1927 – April 3, 1995) was an American mathematician and checkers player. He is considered to be the greatest checkers player who ever lived. Tinsley was world champion 1955–1958 and 1975–1991 and never lo ...

. Ryser contributed to the theory of

combinatorial design Combinatorial design theory is the part of combinatorial mathematics that deals with the existence, construction and properties of systems of finite sets whose arrangements satisfy generalized concepts of ''balance'' and/or ''symmetry''. These co ...

s, finite

set system In set theory and related branches of mathematics, a collection F of subsets of a given set S is called a family of subsets of S, or a family of sets over S. More generally, a collection of any sets whatsoever is called a family of sets, set f ...

s, the

permanent Permanent may refer to: Art and entertainment * ''Permanent'' (film), a 2017 American film * ''Permanent'' (Joy Division album) * "Permanent" (song), by David Cook Other uses * Permanent (mathematics), a concept in linear algebra * Permanent (cy ...

, combinatorial functions, and to many other topics in combinatorics. He served as editor of the journals '' Journal of Combinatorial Theory'', ''

Linear and Multilinear Algebra Linearity is the property of a mathematical relationship (''function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear r ...

'', and ''

Journal of Algebra ''Journal of Algebra'' (ISSN 0021-8693) is an international mathematical research journal in algebra. An imprint of Academic Press, it is published by Elsevier. ''Journal of Algebra'' was founded by Graham Higman, who was its editor from 1964 to ...

''. Ryser's estate funded an endowment creating undergraduate mathematics scholarships at Caltech known as the H. J. Ryser Scholarships.California Tech, "Mathematics Awards", May 17, 1991, page 1. (Scan of that page on-lin
via on-line archives at the newspaper
) The ''Journal of Combinatorial Theory, Series A'' denoted two issues after Ryser's passing as the "Herbert J. Ryser Memorial Issue", parts 1 and 2.

Books

*
Combinatorial Mathematics
' (1963), #14 of the

Carus Mathematical Monographs The ''Carus Mathematical Monographs'' is a monograph series published by the Mathematical Association of America.Drake, Miriam A. (2003). ''Encyclopedia of Library and Information Science: Lib-Pub.'' CRC Press, Books in this series are intended to ...

, published by the Mathematical Association of America. . Republished and translated into several languages. *

Selected papers

* * *

References

{{DEFAULTSORT:Ryser, Herbert John 1923 births 1985 deaths 20th-century American mathematicians University of Wisconsin–Madison alumni California Institute of Technology faculty Ohio State University faculty Combinatorialists