Keyphrases
- query language
- expressive power
- data model
- relational algebra
- conjunctive queries
- future directions
- object oriented
- database
- selected papers
- regular expressions
- xml data
- special case
- acm sigkdd
- panel discussion
- visual query language
- academic researchers
- conference proceedings
- recursive queries
- relational data model
- data complexity
- case study
- data sets