Question: Who was the opponent of Viktor Korchnoi in the 1981 final match on the Candidates Tournament?
Sentence (from "Viktor Korchnoi"): Viktor Lvovich Korchnoi (Russian: Ви́ктор Льво́вич Корчно́й ; ] ; 23 March 1931 – 6 June 2016) was a Soviet (until 1976) and Swiss (since 1994) chess grandmaster and writer.
Relevant evidence: Yes