Regular path queries with constraints
PODS '97 Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Path constraints on semistructured and structured data
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Query rewriting for semistructured data
SIGMOD '99 Proceedings of the 1999 ACM SIGMOD international conference on Management of data
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Optimizing Regular Path Expressions Using Graph Schemas
ICDE '98 Proceedings of the Fourteenth International Conference on Data Engineering
WebOQL: Restructuring Documents, Databases, and Webs
ICDE '98 Proceedings of the Fourteenth International Conference on Data Engineering
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
Efficient algorithms for minimizing tree pattern queries
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
Agent-based processing of navigational queries in INFOWEAVER
Information organization and databases
EDBT '02 Proceedings of the Worshops XMLDM, MDDE, and YRWS on XML-Based Data Management and Multimedia Engineering-Revised Papers
On the Equivalence of XML Patterns
CL '00 Proceedings of the First International Conference on Computational Logic
Rewriting XQL Queries on XML Repositories
BNCOD 17 Proceedings of the 17th British National Conferenc on Databases: Advances in Databases
An analysis of XML database solutions for the management of MPEG-7 media descriptions
ACM Computing Surveys (CSUR)
PTDOM: a schema-aware XML database system for MPEG-7 media descriptions
Software—Practice & Experience - Research Articles
Optimizing the secure evaluation of twig queries
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
Constraints-preserving transformation from XML document type deffinition to relational schema
ER'00 Proceedings of the 19th international conference on Conceptual modeling
Foundations of rule-based query answering
RW'07 Proceedings of the Third international summer school conference on Reasoning Web
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A document type definition (DTD) D defines the structure of elements permitted in any web document valid with respect to D. From a given DTD D we show how to derive a number of simple structural constraints which are implied by D. Using a relational abstraction of web databases, we consider a class of conjunctive queries which retrieve elements from web documents stored in a database D. For simplicity, we assume that all documents in D are valid with respect to the same DTDD. The main contribution of the paper is the use of the constraints derived from D to optimise conjunctive queries on D by removing redundant conjuncts. The relational abstraction allows us to show that the constraints derived from a DTD are equivalent to tuple-generating and equality-generating dependencies which hold on D. Having done so, we can use the chase algorithm to show equivalence between a query and its reduced form.