Keyphrases
- missing information
- incomplete information
- provenance information
- database query languages
- missing data
- query answers
- query processing
- missing values
- query answering
- positive and negative
- query language
- formal semantics
- query evaluation
- feature extraction
- database
- query containment
- data sources
- user queries
- viewpoint
- image retrieval
- expert systems
- pattern recognition
- cooperative
- training data
- image sequences
- decision trees
- aggregate functions
- computer vision
- artificial intelligence