Keyphrases
- question answering
- information retrieval
- natural language processing
- question answering systems
- question classification
- cross language
- qa clef
- natural language
- information extraction
- qa systems
- open domain question answering
- semantic roles
- passage retrieval
- test collection
- answer validation
- retrieval effectiveness
- open domain
- natural language questions
- pseudo relevance feedback
- question answer
- relevance feedback
- data sets