I had intended this week to write about the surprise surge by Mamedyarov which overturned all expectations in the elite Gashimov Memorial. Instead, the death of Viktor Korchnoi, known variously as Viktor the Terrible or the Leningrad Lip, represents a force majeure priority. An outspoken defector and three-times world champion contender, Korchnoi was one of the dominating figures of 20th-century chess.