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Journal of Computer and System Sciences - Special issue: dedicated to the memory of Paris Kanellakis
On the complexity of the containment problem for conjunctive queries with built-in predicates
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Data integration: a theoretical perspective
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On XML integrity constraints in the presence of DTDs
Journal of the ACM (JACM)
CSL '02 Proceedings of the 16th International Workshop and 11th Annual Conference of the EACSL on Computer Science Logic
Tree pattern query minimization
The VLDB Journal — The International Journal on Very Large Data Bases
Answering queries using views: A survey
The VLDB Journal — The International Journal on Very Large Data Bases
XML with data values: typechecking revisited
Journal of Computer and System Sciences - Special issu on PODS 2001
Containment and equivalence for a fragment of XPath
Journal of the ACM (JACM)
ACM SIGMOD Record
Conjunctive queries over trees
Journal of the ACM (JACM)
Representing and querying XML with incomplete information
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Two-Variable Logic on Words with Data
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A system for the static analysis of XPath
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Journal of the ACM (JACM)
Revisiting redundancy and minimization in an XPath fragment
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On the Complexity of Verifying Consistency of XML Specifications
SIAM Journal on Computing
Optimizing Conjunctive Queries over Trees Using Schema Information
MFCS '08 Proceedings of the 33rd international symposium on Mathematical Foundations of Computer Science
Complexity of Data Tree Patterns over XML Documents
MFCS '08 Proceedings of the 33rd international symposium on Mathematical Foundations of Computer Science
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
XML with incomplete information
Journal of the ACM (JACM)
Relational and XML Data Exchange
Relational and XML Data Exchange
Conjunctive query containment over trees
Journal of Computer and System Sciences
Containment of Conjunctive Queries on Annotated Relations
Theory of Computing Systems
Exact XML type checking in polynomial time
ICDT'07 Proceedings of the 11th international conference on Database Theory
On the complexity of query answering over incomplete XML documents
Proceedings of the 15th International Conference on Database Theory
Reasoning about pattern-based XML queries
RR'13 Proceedings of the 7th international conference on Web Reasoning and Rule Systems
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We study static analysis, in particular the containment problem, for analogs of conjunctive queries over XML documents. The problem has been studied for queries based on arbitrary patterns, not necessarily following the tree structure of documents. However, many applications force the syntactic shape of queries to be tree-like, as they are based on proper tree patterns. This renders previous results, crucially based on having non-tree-like features, inapplicable. Thus, we investigate static analysis of queries based on proper tree patterns. We go beyond simple navigational conjunctive queries in two ways: we look at unions and Boolean combinations of such queries as well and, crucially, all our queries handle data stored in documents, i.e., we deal with containment over data trees. We start by giving a general Πp2 upper bound on the containment of conjunctive queries and Boolean combinations for patterns that involve all types of navigation through documents. We then show matching hardness for conjunctive queries with all navigation, or their Boolean combinations with the simplest form of navigation. After that we look at cases when containment can be witnessed by homomorphisms of analogs of tableaux. These include conjunctive queries and their unions over child and next-sibling axes; however, we show that not all cases of containment can be witnessed by homomorphisms. We look at extending tree patterns used in queries in three possible ways: with wildcard, with schema information, and with data value comparisons. The first one is relatively harmless, the second one tends to increase complexity by an exponential, and the last one quickly leads to undecidability.