Deciding containment for queries with complex objects (extended abstract)
PODS '97 Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Query containment for conjunctive queries with regular expressions
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
On the complexity of the containment problem for conjunctive queries with built-in predicates
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Conjunctive-query containment and constraint satisfaction
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Minimization of tree pattern queries
SIGMOD '01 Proceedings of the 2001 ACM SIGMOD international conference on Management of data
Containment and equivalence for an XPath fragment
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Efficient algorithms for minimizing tree pattern queries
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
Containment for XPath Fragments under DTD Constraints
ICDT '03 Proceedings of the 9th International Conference on Database Theory
Reformulation of XML Queries and Constraints
ICDT '03 Proceedings of the 9th International Conference on Database Theory
XPath Containment in the Presence of Disjunction, DTDs, and Variables
ICDT '03 Proceedings of the 9th International Conference on Database Theory
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Efficient algorithms for processing XPath queries
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
ACM SIGMOD Record
FleXPath: flexible structure and full-text querying for XML
SIGMOD '04 Proceedings of the 2004 ACM SIGMOD international conference on Management of data
A Fast Tree Pattern Matching Algorithm for XML Query
WI '04 Proceedings of the 2004 IEEE/WIC/ACM International Conference on Web Intelligence
XML Views as Integrity Constraints and Their Use in Query Translation
ICDE '05 Proceedings of the 21st International Conference on Data Engineering
Rewriting XPath queries using materialized views
VLDB '05 Proceedings of the 31st international conference on Very large data bases
Query caching and view selection for XML databases
VLDB '05 Proceedings of the 31st international conference on Very large data bases
Query optimization in XML structured-document databases
The VLDB Journal — The International Journal on Very Large Data Bases
Accomplishing deterministic XML query optimization
Journal of Computer Science and Technology
Answering tree pattern queries using views
VLDB '06 Proceedings of the 32nd international conference on Very large data bases
Forward node-selecting queries over trees
ACM Transactions on Database Systems (TODS)
The NEXT framework for logical XQuery optimization
VLDB '04 Proceedings of the Thirtieth international conference on Very large data bases - Volume 30
Revisiting redundancy and minimization in an XPath fragment
EDBT '08 Proceedings of the 11th international conference on Extending database technology: Advances in database technology
Minimization of tree pattern queries with constraints
Proceedings of the 2008 ACM SIGMOD international conference on Management of data
Query efficiency in probabilistic XML models
Proceedings of the 2008 ACM SIGMOD international conference on Management of data
On rewriting XPath queries using views
Proceedings of the 12th International Conference on Extending Database Technology: Advances in Database Technology
Rewriting XPath Expressions Depending on Path Summary
ADMA '09 Proceedings of the 5th International Conference on Advanced Data Mining and Applications
SCEND: an efficient semantic cache to adequately explore answerability of views
WISE'06 Proceedings of the 7th international conference on Web Information Systems
Type-based optimization for regular patterns
DBPL'05 Proceedings of the 10th international conference on Database Programming Languages
Caching frequent XML query patterns
APWeb'06 Proceedings of the 2006 international conference on Advanced Web and Network Technologies, and Applications
Efficient processing of multiple XML twig queries
DEXA'06 Proceedings of the 17th international conference on Database and Expert Systems Applications
Rewriting XPath queries using materialized XPath views
Journal of Computer and System Sciences
Foundations of rule-based query answering
RW'07 Proceedings of the Third international summer school conference on Reasoning Web
XPath query satisfiability is in PTIME for real-world DTDs
XSym'07 Proceedings of the 5th international conference on Database and XML Technologies
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XML queries are usually expressed by means of XPath expressions identifying portions of the selected documents. An XPath expression defines a way of navigating an XML tree and returns the set of nodes which are reachable from one or more starting nodes through the paths specified by the expression. The problem of efficiently answering XPath queries is very interesting and has recently received increasing attention by the research community. In particular, an increasing effort has been devoted to define effective optimization techniques for XPath queries. One of the main issues related to the optimization of XPath queries is their minimization. The minimization of XPath queries has been studied for limited fragments of XPath, containing only the descendent, the child and the branch operators. In this work, we address the problem of minimizing XPath queries for a more general fragment, containing also the wildcard operator. We characterize the complexity of the minimization of XPath queries, stating that it is NP-hard, and propose an algorithm for computing minimum XPath queries. Moreover, we identify an interesting tractable case and propose an ad hoc algorithm handling the minimization of this kind of queries in polynomial time.