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Leveraging Lexical Semantics to Infer Context-Free Grammars

Context-free grammars cannot be identified in the limit from positive examples (Gold, 1967), yet natural language grammars are more powerful than context-free grammars and humans learn them with remarkable ease from positive examples (Marcus, 1993). Identifiability results for formal languages ignore a potentially powerful source of information available to learners of natural languages, namely, meanings. This paper explores the learnability of context-free grammars given positive examples and lexical semantics. That is, the learner has a representation of the meaning of each lexical item.