American Go E-Journal

In Memoriam: Leonard Baum

Tuesday June 19, 2018

Note: We just recently learned of the passing of Lenny Baum last year, hence the belated obit below. Please send us any and all go-related news at

Leonard Baum (Lenny, fondly known to many as Opa, and a regular at the annual U.S. Go Congress), died unexpectedly at the2018.06.19_LeonardBaum age of 86 on August 14, 2017 at his home in Princeton, NJ. He graduated Phi Beta Kappa, summa cum laude in mathematics, from Harvard University in 1953 and received a PhD in Mathematics from Harvard in 1958. He worked for a couple of years at the University of Chicago before moving to Princeton, NJ to work at the Institute for Defense Analysis – a Defense Department think tank which specialized in cryptography. Lenny’s affiliation with IDA in Princeton spanned 1959 through 1978. He wrote over 100 internal papers there and is responsible for what has become the motto of IDA: “No idea is bad. A bad idea is good. A good idea is terrific.” Lenny’s public scientific legacy includes the Baum-Welch algorithm, which directly enabled the first effective speech recognition systems. Today, 50 years later, this work remains at the center of these systems – while its mathematical and algorithmic descendants and other relatives, have impacted many fields from genomics to weather prediction to finance. After leaving IDA, Lenny teamed up with Jim Simons to apply his mathematical modeling to the financial markets. He retired early, legally blind, seeing with only his rods, having lost all his cones to a dystrophy, but that didn’t stop him from travelling the world over, visiting many exotic places. He continued to trade for himself very successfully, often taking very contrarian positions. An avid go player, deep lover of science and seeker of truth, he continued working on math literally up until his death, spending the night before he died reading new math papers on prime numbers. “His greatest pleasure came from facing an opponent many decades younger – often losing but – like the kindly grandfather he was – enjoying every moment of the encounter,” says Terry Benson. The Leonard Baum Prizes are being established in his memory to encourage inter-generational play. “Lenny became part of the mid-Jersey go scene that flourished in the heady world around Princeton’s Institute for Defense Analysis and Institute for Advanced Study,” Benson added. “His visual affliction forced him to track his head inches over the board but was at least partially suited to go. With only rods and no cones he could see what you need to in go: black and white.”

-  Includes reporting originally published in The New York Times on Aug. 18, 2017. photo by Phil Straus