Richard V. Allen, President Ronald Reagan’s first national security adviser, who was forced to resign after less than a year in office, much of it under a cloud of controversies that muted his voice in contributing to foreign and military policies,

Richard Hamilton, an inventive mathematician who devised the Ricci flow, a groundbreaking equation that helped advance understanding of the fundamental nature of three-dimensional space, died on Sept. 29 in Manhattan. He was 81. The death, in a hosp