A Proof Procedure for Data Dependencies
Journal of the ACM (JACM)
STRUDEL: a Web site management system
SIGMOD '97 Proceedings of the 1997 ACM SIGMOD international conference on Management of data
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 decidability of query containment under constraints
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Rewriting of regular expressions and regular path queries
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
WWW '99 Proceedings of the eighth international conference on World Wide Web
Equivalences Among Relational Expressions with the Union and Difference Operators
Journal of the ACM (JACM)
Data on the Web: from relations to semistructured data and XML
Data on the Web: from relations to semistructured data and XML
Expressive and efficient pattern languages for tree-structured data (extended abstract)
PODS '00 Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
SIGMOD '00 Proceedings of the 2000 ACM SIGMOD international conference on Management of data
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
Tableau Techniques for Querying Information Sources through Global Schemas
ICDT '99 Proceedings of the 7th International Conference on Database Theory
An Equational Chase for Path-Conjunctive Queries, Constraints, and Views
ICDT '99 Proceedings of the 7th International Conference on Database Theory
Algebraic Rewritings for Optimizing Regular Path Queries
ICDT '01 Proceedings of the 8th International Conference on Database Theory
An Optimization Technique for Answering Regular Path Queries
Selected papers from the Third International Workshop WebDB 2000 on The World Wide Web and Databases
Physical Data Independence, Constraints, and Optimization with Universal Plans
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Data integration: a theoretical perspective
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Reformulation of XML Queries and Constraints
ICDT '03 Proceedings of the 9th International Conference on Database Theory
View-Based Query Answering and Query Containment over Semistructured Data
DBPL '01 Revised Papers from the 8th International Workshop on Database Programming Languages
Tree pattern query minimization
The VLDB Journal — The International Journal on Very Large Data Bases
Query containment and rewriting using views for regular path queries under constraints
Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Reasoning on regular path queries
ACM SIGMOD Record
XML Queries and constraints, containment and reformulation
Theoretical Computer Science - Database theory
Data exchange: semantics and query answering
Theoretical Computer Science - Database theory
Quasi-inverses of schema mappings
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
MARS: a system for publishing XML from mixed and redundant storage
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
Quasi-inverses of schema mappings
ACM Transactions on Database Systems (TODS)
Graceful database schema evolution: the PRISM workbench
Proceedings of the VLDB Endowment
Reverse data exchange: coping with nulls
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Inverting schema mappings: bridging the gap between theory and practice
Proceedings of the VLDB Endowment
Effective pruning for XML structural match queries
Data & Knowledge Engineering
Expressive languages for path queries over graph-structured data
Proceedings of the twenty-ninth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Relative expressive power of navigational querying on graphs
Proceedings of the 14th International Conference on Database Theory
Reverse data exchange: Coping with nulls
ACM Transactions on Database Systems (TODS)
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Querying semantic web data with SPARQL
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
The complexity of evaluating path expressions in SPARQL
PODS '12 Proceedings of the 31st symposium on Principles of Database Systems
Regular path queries on graphs with data
Proceedings of the 15th International Conference on Database Theory
Graph Logics with Rational Relations and the Generalized Intersection Problem
LICS '12 Proceedings of the 2012 27th Annual IEEE/ACM Symposium on Logic in Computer Science
Expressive Languages for Path Queries over Graph-Structured Data
ACM Transactions on Database Systems (TODS)
Definability problems for graph query languages
Proceedings of the 16th International Conference on Database Theory
Spanners: a formal framework for information extraction
Proceedings of the 32nd symposium on Principles of database systems
Proceedings of the 32nd symposium on Principles of database systems
Expressiveness and static analysis of extended conjunctive regular path queries
Journal of Computer and System Sciences
The complexity of regular expressions and property paths in SPARQL
ACM Transactions on Database Systems (TODS) - Invited papers issue
Querying Regular Graph Patterns
Journal of the ACM (JACM)
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We are interested in the theoretical foundations of the optimization of conjunctive regular path queries (CRPQs). The basic problem here is deciding query containment both in the absence and presence of constraints. Containment without constraints for CRPQs is EXPSPACE-complete, as opposed to only NP-complete for relational conjunctive queries. Our past experience with implementing similar algorithms suggests that staying in PSPACE might still be useful. Therefore we investigate the complexity of containment for a hierarchy of fragments of the CRPQ language. The classifying principle of the fragments is the expressivity of the regular path expressions allowed in the query atoms. For most of these fragments, we give matching lower and upper bounds for containment in the absence of constraints. We also introduce for every fragment a naturally corresponding class of constraints in whose presence we show both decidability and undecidability results for containment in various fragments. Finally, we apply our results to give a complete algorithm for rewriting with views in the presence of constraints for a fragment that contains Kleene-star and disjunction.