Copyright 2005 Chicago Sun-Times, Inc. Chicago Sun-Times April 22, 2005 Friday SECTION: NEWS; Pg. 80 LENGTH: 784 words HEADLINE: Saunders Mac Lane, pioneering mathematician BYLINE: RUMMANA HUSSAIN BODY: Saunders Mac Lane, the prominent University of Chicago mathematician and National Medal of Science recipient, helped create the category theory that deals with mathematical structures and relationships between them. Mr. Mac Lane, who is often hailed as one of the most influential American mathematicians of the 20th century, died April 14 from internal bleeding related to complications with constrictive heart disease at the Mission Villa hospice in Daly City, Calif. He was 95. He began laying down the foundation of the revolutionary theory in a landmark paper he and fellow mathematician Samuel Eilenberg published in 1945. "There are very few mathematicians who ever introduced a completely new theory into the field. That's really rare," said Klaus Peters, a publisher at A K Peters Ltd., which is releasing Mr. Mac Lane's autobiography next month. The category theory, which has influenced most math-related fields including computer science, was first dismissed by more practical minded mathematicians as too abstract to be useful. So when Mr. Mac Lane wrote a book on the theory, he titled it Categories for the Working Mathematician just to poke fun at his detractors. "He had a great sense of humor. He had a very forceful personality. He was very opinionated. He was usually right -- not always -- but he was always subject to persuasion. He listened to people," U of C math professor J. Peter May said. The Norwich, Conn. native, who published 100 research papers and six books, received a bachelor's degree at Yale in 1930 and a master's degree from the University of Chicago in 1931. Mr. Mac Lane received his Ph.D. at the University at Gottingen, Germany in 1934. There, he studied under the renowned mathematicians Hermann Weyl and Paul Bernays. Between the mid-1930s to late 1940s, Mr. Mac Lane taught math at Harvard, Cornell and the University of Chicago before finally choosing the latter as his longtime professional home in 1947 where he lectured on logic, topology and alegebraic theories. He retired in the 1980s, but continued to advise students until the 1990s. While at the U. of C., Mr. Mac Lane served as chairman of the mathematical department between 1952 to 1958 and supervised 39 Ph.D students. During his career, the Fulbright Scholar was honored by numerous fellowships, honorary degrees and awards, including the University of Chicago Alumni Association's Norman Maclean Faculty Award in 2003. In 1989, former President George H.W. Bush bestowed him with the National Medal of Science, the country's highest award for scientific achievement. Mr. Mac Lane always strived to use science to better the country. As a member of the National Science Board, he provided science policy advice to the U.S. government between 1974 and 1980 and in the mid-1940s, he directed Columbia University's Applied Mathematics Group, which was involved in the war effort. "He was an extremely powerful person, who stood up for raising the level of a scientific atmosphere in the whole country," said F. William Lawvere, a retired professor at the State University of New York at Buffalo. Mr. Mac Lane also served as vice president of the National Academy of Sciences and the American Philosophical Society. He also was past president of the Mathematical Association of America and the American Mathematical Society. Mr. Mac Lane, an avid skier who also loved to sail, was described by friends and colleagues as an energetic man who valued hard work. He out-hiked a younger Lawvere in Aspen in his 70s and would insist on walking to his third-floor office at the U. of C. well into his 80s. "When he was 90, I saw him on a Friday night out in the street, and I asked him if he wanted to go to a conference at Northwestern University the next day on the higher category theory. He said, 'yes, please,' and called me the next day at 7 a.m. to make sure I hadn't forgotten him. He sat in the front row and asked questions the whole weekend," May said. Mr. Mac Lane was always dedicated to helping students and would often go out of his way to assist them with their thesis papers, even if they didn't relate to his own research. His textbook written with Garrett Birkhoff, A Survey of Modern Algebra, has been used by college students for years. "I failed physics, so he tutored me. Thanks to him, I was able to understand it," said Gretchen MacLane, Mr. Mac Lane's daughter with his late wife, Dorothy Jones. "He was a wonderful tutor." Her also is survived by his wife, Osa; his other daughter, Cynthia Hay; his stepdaughter, Karen Segal; his stepsons, Andrew and William Segal; his grandson and five stepgrandchildren. Funeral services have been held. 27-Apr-2005 13:04:19 -0300,2053;000000000000-0000001c