Object identity as a query language primitive
SIGMOD '89 Proceedings of the 1989 ACM SIGMOD international conference on Management of data
Subsumption in KL-ONE is undecidable
Proceedings of the first international conference on Principles of knowledge representation and reasoning
Implication problems for functional constraints on databases supporting complex objects
Journal of Computer and System Sciences
What can knowledge representation do for semi-structured data?
AAAI '98/IAAI '98 Proceedings of the fifteenth national/tenth conference on Artificial intelligence/Innovative applications of artificial intelligence
Storing semistructured data with STORED
SIGMOD '99 Proceedings of the 1999 ACM SIGMOD international conference on Management of data
XML-based information mediation with MIX
SIGMOD '99 Proceedings of the 1999 ACM SIGMOD international conference on Management of data
Data on the Web: from relations to semistructured data and XML
Data on the Web: from relations to semistructured data and XML
Regular path queries with constraints
Journal of Computer and System Sciences
The object data standard: ODMG 3.0
The object data standard: ODMG 3.0
Path constraints in semistructured databases
Journal of Computer and System Sciences - Special issue on the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on principles of database systems
Proceedings of the 10th international conference on World Wide Web
On XML integrity constraints in the presence of DTDs
PODS '01 Proceedings of the twentieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
XML with data values: typechecking revisited
PODS '01 Proceedings of the twentieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
On verifying consistency of XML specifications
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Database Management Systems
Reasoning About Equations and Functional Dependencies on Complex Objects
IEEE Transactions on Knowledge and Data Engineering
Relational Databases for Querying XML Documents: Limitations and Opportunities
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
Answering XML Queries on Heterogeneous Data Sources
Proceedings of the 27th International Conference on Very Large Data Bases
Physical Data Independence, Constraints, and Optimization with Universal Plans
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
Reasoning in expressive description logics
Handbook of automated reasoning
Constraints-preserving transformation from XML document type deffinition to relational schema
ER'00 Proceedings of the 19th international conference on Conceptual modeling
ACM SIGMOD Record
Semantic query optimization in the presence of types
Proceedings of the twenty-ninth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Consistency of XML specifications
Inconsistency Tolerance
Semantic query optimization in the presence of types
Journal of Computer and System Sciences
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Path constraints are capable of expressing inclusion and inverse relationships and have proved useful in modeling and querying semistructured data [Abiteboul and Vianu 1999; Buneman et al. 2000]. Types also constrain the structure of data and are commonly found in traditional databases. There has also been work on imposing structure or a type system on semistructured data for storing and querying semistructured data in a traditional database system [Alon et al. 2001; Deutsch et al. 1999a; Florescu and Kossmann 1999; Shanmugasundaram et al. 1999]. One wants to know whether complexity results for reasoning about path constraints established in the untyped (semistructured) context could carry over to traditional databases, and vice versa. It is therefore appropriate to understand the interaction between types and path constraints. In addition, XML [Bray et al. 1998], which may involve both an optional schema (e.g., DTDs or XML Schema [Thompson et al. 2001]) and integrity constraints, highlights the importance of the study of the interaction.This article investigates that interaction. In particular it studies constraint implication problems, which are important both in understanding the semantics of type/constraint systems and in query optimization. It shows that path constraints interact with types in a highly intricate way. For that purpose a number of results on path constraint implication are established in the presence and absence of type systems. These results demonstrate that adding a type system may in some cases simplify reasoning about path constraints and in other cases make it harder. For example, it is shown that there is a path constraint implication problem that is decidable in PTIME in the untyped context, but that becomes undecidable when a type system is added. On the other hand, there is an implication problem that is undecidable in the untyped context, but becomes not only decidable in cubic time but also finitely axiomatizable when a type system is imposed.