A Constraint Grammar Based Question Answering System for Portuguese

This paper describes a linguistic, NLP based Information Extraction (IE) system for Portuguese text. The system focuses on the natural language Question Answering task (QA) and relies on full syntactic tree parses, exploiting both lexico-semantic information, syntactic pattern matching and named entity subtyping. Context driven Constraint Grammar rules (CG) are used not only for PoS disambiguation, but also to assign word based function tags and semantic categories. Exact QA matches are supplemented by iterative textual and syntactic relaxation of seach phrases and hit sentence chunks.