BOLESLAVSKI, ISAAC (1919–1977), Russian chess grandmaster. Boleslavski was born in Ukraine. He established himself early as one of the leading players in the U.S.S.R. He achieved his greatest success in the Candidates' Tournament at Budapest in 1950, where he shared first prize with David *Bronstein. The latter won the play-off and thus qualified to challenge Mikhail *Botvinnik. From that time on Boleslavski distinguished himself in important tournaments. He also achieved celebrity as an analyst of chess openings, and many important variations resulted from his experiments in practical play.