Herbert John Ryser (July 28, 1923 – July 12, 1985) was a professor of mathematics, widely regarded as one of the major figures in

combinatorics Combinatorics is an area of mathematics primarily concerned with counting, both as a means and an end in obtaining results, and certain properties of finite structures. It is closely related to many other areas of mathematics and has many appl ...

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 The Bruck– Ryser– Chowla theorem is a result on the combinatorics of block designs that implies nonexistence of certain kinds of design. It states that if a (''v'', ''b'', ''r'', ''k'', λ)-design exists with ''v = b'' (a symmetric block de ...

Ryser's formula 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 simi ...

for the computation of the permanent of a matrix, 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, t ...

.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 scholar ...

, then joined the faculty of

. In 1962 he took a professorship at

Syracuse University Syracuse University (informally 'Cuse or SU) is a Private university, private research university in Syracuse, New York. Established in 1870 with roots in the Methodist Episcopal Church, the university has been nonsectarian since 1920. Locate ...

, 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 R. A. Brualdi is a professor emeritus of combinatorial mathematics at the University of Wisconsin–Madison. Brualdi received his Ph.D. from Syracuse University in 1964; his advisor was H. J. Ryser. Brualdi is an Editor-in-Chief of the Electroni ...

, Clement W. H. Lam, and Marion Tinsley. Ryser contributed to the theory of combinatorial designs, 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 fami ...

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 The ''Journal of Combinatorial Theory'', Series A and Series B, are mathematical journals specializing in combinatorics and related areas. They are published by Elsevier. ''Series A'' is concerned primarily with structures, designs, and applicat ...

'', '' Linear and Multilinear Algebra'', and '' Journal of Algebra''. 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, published by the

Mathematical Association of America The Mathematical Association of America (MAA) is a professional society that focuses on mathematics accessible at the undergraduate level. Members include university, college, and high school teachers; graduate and undergraduate students; pure a ...

. . 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