Albert Nijenhuis, professor emeritus of mathematics at Penn, died on February 13 after a long illness in Seattle, Washington. He was 88 years old. Dr. Nijenhuis was born in the Netherlands. After an interruption in his studies due to World War II, he received his PhD in mathematics from the University of Amsterdam in 1952. He came to the United States as a Fulbright Fellow at Princeton, then spent two years at Princeton’s Institute for Advanced Study. He was an instructor at the University of Chicago and an assistant professor and then professor of mathematics at the University of Washington in Seattle. From 1961 to 1962, he returned to the Institute for Advanced Study as a John Simon Guggenheim fellow (Almanac April 30, 1996). He was recruited to Penn’s faculty in 1963, then spent a year as a Fulbright professor at the University of Amsterdam before joining Penn as a professor of mathematics in 1964. Dr. Nijenhuis’s original mathematical interest was in differential geometry, in which he made several significant contributions, particularly the Nijenhuis tensor and its applications to the theory of deformations. He later discovered an interest in combinatorial analysis and formed an influential and powerful team with his colleague, the late Herbert Wilf, with whom he published multiple books. Dr. Nijenhuis was an invited speaker at the International Mathematical Congress in Edinburgh, Scotland in 1958. He became a correspondent member of the Royal Netherlands Academy of Arts & Sciences in 1966. In the fall of 1977, he researched and conducted a seminar in combinatorial mathematics as a visiting professor at Dartmouth College (Almanac October 25, 1977). In 2012, he was named to the inaugural class of fellows of the American Mathematical Society (Almanac December 18, 2012). Dr. Nijenhuis took early retirement from Penn in 1987 and moved back to his beloved Pacific Northwest. In his later years, as an affiliate professor at the University of Washington, he rekindled his interest in differential geometry and presented a paper at age 70. Dr. Nijenhuis is survived by his wife, Marianne; four daughters, Erika, Karin, Sabien and Alaine and their husbands; and six grandchildren.
