Grigori Yakovlevich PerelmanPerelman, Grigori Yakovlevich, 1966–, Russian mathematician. After doing graduate work in the late 1980s for his Candidate of Science degree from Leningrad State Univ. (now St. Petersburg State Univ.), he worked as a researcher at the Steklov Institute of Mathematics, St. Petersburg, and held postdoctorate positions at several U.S. universities in the early 1990s. In 1995 he returned to the Steklov Institute. In 2002–3 Perelman posted three papers on the Internet that sketched a proof of the Poincaré conjecture, a fundamental question in topology. Building on and refining the insights of U.S. mathematician Richard Hamilton, Perelman proved both Henri Poincaré's conjecture (1904) that all closed, simply connected threedimensional manifolds (mathematical spaces) are topologically equivalent to a threedimensional sphere and the broader Thurston geometrization conjecture. Perelman was awarded the Fields Medal (2006) and the Clay Mathematics Institute Millenium Prize (2010) for his work, both of he refused. After 2003 the unconventional Perelman increasingly withdrew from academic work; he resigned from the Steklov Institute in 2006. See studies by D. O'Shea (2007) and M. Gessen (2009). The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved. See more Encyclopedia articles on: Mathematics: Biographies 
