Thomas L. Saaty, a former professor of statistics and operations research at Wharton, died on August 20. He was 91.

Dr. Saaty, a well-known and recognized mathematician who created the Analytical Hierarchy Process, worked for the federal Arms Control and Disarmament Agency before joining Wharton in 1969 as a professor. While at Penn, he was chairman of the graduate group in operations research and a member of the graduate group in peace research (Almanac April 10, 1970). He briefly held a secondary appointment in decision sciences (Almanac January 23, 1979). He resigned in 1979 and went on to develop groundbreaking theories on strategic decision-making and resource allocation at University of Pittsburgh.

Dr. Saaty is survived by his wife, Rozann and his children, John, Daniel, Michael, Emily Harker and Linda Holker; 10 grandchildren; and three great-grandchildren.