More complicated questions about maxima and minima, and some closures of NP
Theoretical Computer Science
SIAM Journal on Computing
Discrete Mathematics - Algebraic graph theory; a volume dedicated to Gert Sabidussi
Principles of distributed database systems (2nd ed.)
Principles of distributed database systems (2nd ed.)
Minimization of tree pattern queries
SIGMOD '01 Proceedings of the 2001 ACM SIGMOD international conference on Management of data
Constraint Satisfaction, Bounded Treewidth, and Finite-Variable Logics
CP '02 Proceedings of the 8th International Conference on Principles and Practice of Constraint Programming
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Monadic datalog and the expressive power of languages for Web information extraction
Journal of the ACM (JACM)
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
OptimAX: Optimizing Distributed ActiveXML Applications
ICWE '08 Proceedings of the 2008 Eighth International Conference on Web Engineering
ACM Computing Surveys (CSUR)
Satisfiability and relevance for queries over active documents
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Satisfiability of downward XPath with data equality tests
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Complexity of K-tree structured constraint satisfaction problems
AAAI'90 Proceedings of the eighth National conference on Artificial intelligence - Volume 1
On the equivalence of distributed systems with queries and communication
Proceedings of the 14th International Conference on Database Theory
A framework for distributed XML data management
EDBT'06 Proceedings of the 10th international conference on Advances in Database Technology
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Distributed data management systems consist of peers that store, exchange and process data in order to collaboratively achieve a common goal, such as evaluating some query. We study the equivalence of such systems. We model a distributed system by a collection of Active XML documents, i.e., trees augmented with function calls for performing tasks such as sending, receiving and querying data. As our model is quite general, the equivalence problem turns out to be undecidable. However, we exhibit several restrictions of the model, for which equivalence can be effectively decided. We also study the computational complexity of the equivalence problem, and present an axiomatization of equivalence, in the form of a set of equivalence-preserving rewrite rules allowing us to optimize a system by rewriting it into an equivalent, but possibly more efficient system.