Not many grandmasters were allowed to emigrate , and after Viktor Korchnoi defected in 1976 , the door was almost completely shut until the fall of the Soviet Union 15 years later .
Viktor Korchnoi /people/person/nationality Soviet Union
RB JJ NNS VBD VBN TO VB , CC IN NNP NNP VBD IN CD , DT NN VBD RB RB VBN IN DT NN IN DT NNP NNP CD NNS RB .
Viktor Korchnoi
PERSON
Soviet Union
LOCATION
/people/person/nationality