sentence1: in a restricted form of indexed grammars was discussed in which the stack associated with the nonterminal on the left of each production can only be associated with one of the occurrences of nonterminals on the right of the production .
sentence2: gazdar discussed a restricted form of indexed grammars in which the stack associated with the nonterminal on the left of each production can only be associated with one of the occurrences of nonterminals on the right of the production .