Possibilities and limitations of using flat operators in nested algebra expressions
Proceedings of the seventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
First-order logic with two variables and unary temporal logic
Information and Computation - Special issue: LICS'97
On the complexity of nonrecursive XQuery and functional query languages on complex values
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Arithmetic, first-order logic, and counting quantifiers
ACM Transactions on Computational Logic (TOCL)
Efficient algorithms for processing XPath queries
ACM Transactions on Database Systems (TODS)
First order paths in ordered trees
ICDT'05 Proceedings of the 10th international conference on Database Theory
On the complexity of nonrecursive XQuery and functional query languages on complex values
ACM Transactions on Database Systems (TODS)
Expressiveness and complexity of xml publishing transducers
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
On the expressibility of functions in XQuery fragments
Information Systems
Expressiveness and complexity of XML publishing transducers
ACM Transactions on Database Systems (TODS)
From XQuery to relational logics
ACM Transactions on Database Systems (TODS)
Schema-based independence analysis for XML updates
Proceedings of the VLDB Endowment
Foundations of XML based on logic and automata: a snapshot
FoIKS'12 Proceedings of the 7th international conference on Foundations of Information and Knowledge Systems
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We establish correspondences between top-down tree building query languages and predicate logics. We consider the expressive power of the query language XQ, a clean core of the practitioner's language XQuery. We show that all queries in XQ with only atomic equality are equivalent to “first-order interpretations”, an analog to first-order logic (FO) in the setting of transformations of tree-structured data. When XQ is considered with deep equality, we find that queries can be translated into FO with counting (FO(Cnt)). We establish partial converses to this, characterizing the subset of the FO resp. FO(Cnt) interpretations that correspond to XQ. Finally, we study the expressive power of fragments of XQ and obtain partial characterizations in terms of existential FO and a fragment of FO that is two-variable if the tree node labeling alphabet is assumed fixed