Source: University of Toronto
In memoriam: Professor Emeritus Alfred LehmanLehman was brilliant researcher
October 24, 2006
Professor Emeritus Alfred Lehman of mathematics and computer science died May 8 after a long struggle with diabetes. He was 74 years old.
Lehman received his PhD from the University of Florida in 1954 and worked at Tulane University, the Massachusetts Institute of Technology, the Case Institute, the University of Wisconsin, Rensselaer Polytechnic Institute and the Walter Reed Institute before joining the University of Toronto faculty as a professor of mathematics and computer science in 1965.
A remarkable researcher, Lehmanís area of expertise was discrete and combinatorial mathematics, specifically network and graph theory, integer optimization, matroids and lattices, all subjects of major interest to both computer science and mathematics.
Although continuing health problems caused him to take disability leave in his latter years, limiting his publication output and ability to supervise students, it is the quality of his work that ensures his research will continue to be remembered as highly significant. Referee reports on his papers described his work as being "deep" and "brilliant." In 1991 he received a prestigious Delbert Ray Fulkerson Prize, given for outstanding papers in the area of discrete mathematics by the American Mathematical Society and the Mathematical Programming Society. It was awarded for his paper on width-length inequality and degenerate projective planes, solving in great generality an open problem in combinatorial algorithms that had long resisted solution.
Lehman did not allow his deteriorating health to limit his active mind and continued to participate and contribute to seminars in both departments, even after he ceased teaching.
"Al was a regular attendee at a broad range of computer science and mathematics seminars. Having known him for over 40 year, I cannot remember Al arriving at, or leaving, a seminar early," said Professor Derek Corneil of computer science.
Professor Emeritus Calvin Gotlieb, a longtime friend and colleague, said Lehman was "a gentle, modest man." At Lehmanís memorial service, Gotlieb recalled, there was a moving tribute from the leader of Torontoís amateur radio club, revealing that Lehman had been a teacher and mentor to generations of amateur radio buffs who wished to participate and contribute to the valuable public services these clubs still provide. "Until then, even Lehmanís closest colleagues had not known of his involvement."