18 September 2003

Another report on Robbins before his death:

http://mathforum.org/epigone/math-learn/zhyplinglau

The New York Times, September 18, 2003

**By ANAHAD O'CONNOR**

Dr. David P. Robbins, a mathematician who broke codes and cryptological problems for the government and devised an algebraic formula that became widely recognized in the mathematical world, died on Sept. 4 at his home in Princeton, N.J. He was 61.

The cause was pancreatic cancer, his family said.

As a mathematician with the Institute for Defense Analyses, which provides research to the Defense Department, Dr. Robbins worked on making and breaking codes. Many of the codes and problems he deciphered were deemed intractable by the National Security Agency, and his solutions often earned him awards from the government.

Much of that work remains classified and has never been described to the public. But in 1996, he received the security agency's Exceptional Service Medal for his contributions to national security, an honor rarely bestowed by the agency.

"He would frequently come up with new ways of solving complex mathematical equations," said Dr. Lieberman, former director of the institute's Center for Communications Research. "There were a lot of projects where the N.S.A. would anticipate spending millions of dollars and David would come up with a way of solving it for only thousands. Then he would teach others how to use those same methods he came up with."

David Peter Robbins was born in Brooklyn on Aug. 12, 1942. He received his bachelor's degree from Harvard and his Ph.D. from the Massachusetts Institute of Technology. He taught at Phillips Exeter Academy and at Washington and Lee University, among others, before joining the defense institute in 1980.

He is survived by his wife, Deborah; a son, Matthew Eli, of Princeton; his stepmother, Sheila Robbins of New York; two sisters, Marjorie Robbins Friedlander of Pacific Palisades, Calif., and Ann Aknin of Dana Point, Calif.; a half brother, Peter Robbins of New York; a stepbrother, Thomas Hardy of Worcester, Mass.; and two stepsisters, Barbara Morgan of Sayreville, N.J., and Meredith Hardy of Palm Desert, Calif.

Dr. Robbins also did important nongovernmental work in algebra and number theory. In the early 80's, he came up with a formula for predicting numbers of alternating-sign matrices, an algebraic problem resulting from work done in 1866 by Charles Dodgson, better known as Lewis Carroll, the author of "Alice's Adventures in Wonderland."

It took mathematicians more than a decade to figure out a proof for it, but today Dr. Robbins's formula has applications in fields like quantum mechanics, computational algebra and abstract mathematical symmetry.

After learning earlier this year that he had cancer, Dr. Robbins decided to try to crack one last problem: finding the area of a polygon given only the lengths of its sides.

Dr. Robbins published formulas for pentagons and hexagons in 1994, but finding a general formula for a polygon with any number of sides, last known to have been tried by the 19th-century mathematician August Ferdinand Möbius, eluded him for decades.

Despite chemotherapy, he came up with partial solutions to the formula, said Dr. Maureen Quirk, a colleague of Dr. Robbins's at the defense analyses institute. But he died before he could reach a complete answer.