Keyphrases
- question answering
- passage retrieval
- information retrieval
- sentence retrieval
- information extraction
- question answering systems
- natural language processing
- question classification
- natural language
- natural language questions
- qa clef
- syntactic information
- named entities
- answer validation
- cross language
- relation extraction
- relevance feedback
- retrieval systems
- test collection
- machine learning
- answer extraction
- image retrieval
- textual entailment recognition
- retrieval model
- query expansion