Structural Properties of XPath Fragments
ICDT '03 Proceedings of the 9th International Conference on Database Theory
The complexity of XPath query evaluation
Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Theoretical Computer Science - Database theory
Conditional XPath, the first order complete XPath dialect
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Deciding well-definedness of XQuery fragments
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
On the complexity of nonrecursive XQuery and functional query languages on complex values
ACM Transactions on Database Systems (TODS)
Interpreting tree-to-tree queries
ICALP'06 Proceedings of the 33rd international conference on Automata, Languages and Programming - Volume Part II
XTaGe: A Flexible Generation System for Complex XML Collections
DEXA '09 Proceedings of the 20th International Conference on Database and Expert Systems Applications
Information Sciences: an International Journal
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XQuery is a powerful XML query language with many features and syntactic constructs. For many common queries we do not need all the expressive power of XQuery. We investigate the effect of omitting certain features of XQuery on the expressive power of the language. We start from a simple base fragment which can be extended by several optional features being aggregation functions such as count and sum, sequence generation, node construction, position information in for loops, and recursion. In this way we obtain 64 different XQuery fragments which can be divided into 17 different equivalence classes such that two fragments can express the same functions if they are in the same equivalence class. Moreover, we investigate the relationships between these equivalence classes and derive some properties of the fragments within these equivalence classes.