#### Mathematician Dennis Ray Estes Dies at 57

Estes, a professor of mathematics in the USC College of Letters, Arts and Sciences, was a leading expert in the arithmetic theory of quadratic forms over rings of algebraic integers. He wrote more than 40 papers on quadratic forms, number theory, linear and commutative algebra with such co-authors as Len Adleman and Bob Guralnick at USC, Hyman Bass at Columbia University, John Hsia at Ohio State and Olga Taussky at Caltech.

“Professor Estes served as the mathematics department’s vice chairman for graduate studies for 12 years,” said Susan Montgomery, current chair of the USC mathematics department. “He was a constant source of help and advice to our graduate students. He also had six Ph.D. students of his own, as well as several master’s degree students, and he served on the university’s graduate advisory committee.”

DENNIS RAY ESTES was born June 18, 1941, in Ada, Okla. He was reared in Ada, where he attended public schools and earned a bachelor’s degree at East Central University in 1971. He earned a master’s degree at Louisiana State University in 1963 and a Ph.D., under the direction of Gordan Pall, at LSU in 1965. He was a Bateman Research Fellow at Caltech from 1966 to 1968, when he joined the mathematics faculty at USC.

Estes was a major speaker at several international conferences in Germany and France and, most recently, at a meeting on Quadratic Forms and Lattices in Seoul, Korea, last June.

Estes is survived by his wife, Lee, and two daughters, Darcy and Shelly, of Pasadena; his mother, of Ada, Okla.; two sisters and a brother.

IN RECOGNITION OF his service to the mathematics community and to graduate students, the USC mathematics department has established the Dennis Ray Estes Graduate Memorial Fund to benefit graduate students in mathematics. Donations may be sent to the Department of Mathematics, University of Southern California, Los Angeles, CA 90089-1113.