Readings in nonmonotonic reasoning
Readings in nonmonotonic reasoning
Principles of database and knowledge-base systems, Vol. I
Principles of database and knowledge-base systems, Vol. I
A note on the reduction of two-way automata to one-way atuomata
Information Processing Letters
On the complexity of H-coloring
Journal of Combinatorial Theory Series B
Equivalence of datalog queries is undecidable
Journal of Logic Programming
Answering queries using views (extended abstract)
PODS '95 Proceedings of the fourteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Answering queries using templates with binding patterns (extended abstract)
PODS '95 Proceedings of the fourteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Query caching and optimization in distributed mediator systems
SIGMOD '96 Proceedings of the 1996 ACM SIGMOD international conference on Management of data
A query language and optimization techniques for unstructured data
SIGMOD '96 Proceedings of the 1996 ACM SIGMOD international conference on Management of data
Rewriting queries using views in description logics
PODS '97 Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Answering recursive queries using views
PODS '97 Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
PODS '97 Proceedings of the sixteenth 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
Complexity of answering queries using materialized views
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Catching the boat with Strudel: experiences with a Web-site management system
SIGMOD '98 Proceedings of the 1998 ACM SIGMOD international conference on Management of data
Database techniques for the World-Wide Web: a survey
ACM SIGMOD Record
Rewriting aggregate queries using views
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
Rewriting of regular expressions and regular path queries
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-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
WWW '99 Proceedings of the eighth international conference on World Wide Web
On the Structure of Polynomial Time Reducibility
Journal of the ACM (JACM)
View-based query processing for regular path queries with inverse
PODS '00 Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
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
Querying Semistructured Heterogeneous Information
DOOD '95 Proceedings of the Fourth International Conference on Deductive and Object-Oriented Databases
Query Folding with Inclusion Dependencies
ICDE '98 Proceedings of the Fourteenth International Conference on Data Engineering
Optimizing Regular Path Expressions Using Graph Schemas
ICDE '98 Proceedings of the Fourteenth International Conference on Data Engineering
Optimizing Queries with Materialized Views
ICDE '95 Proceedings of the Eleventh International Conference on Data Engineering
Information Integration Using Logical Views
ICDT '97 Proceedings of the 6th International Conference on Database Theory
ICDT '97 Proceedings of the 6th International Conference on Database Theory
Adding Structure to Unstructured Data
ICDT '97 Proceedings of the 6th International Conference on Database Theory
Tableau Techniques for Querying Information Sources through Global Schemas
ICDT '99 Proceedings of the 7th International Conference on Database Theory
Answering Queries Using Materialized Views with Disjunctions
ICDT '99 Proceedings of the 7th International Conference on Database Theory
Index Structures for Path Expressions
ICDT '99 Proceedings of the 7th International Conference on Database Theory
Obtaining Complete Answers from Incomplete Databases
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
Answering Queries with Aggregation Using Views
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
The GMAP: a versatile tool for physical data independence
The VLDB Journal — The International Journal on Very Large Data Bases
The complexity of relational query languages (Extended Abstract)
STOC '82 Proceedings of the fourteenth annual ACM symposium on Theory of computing
The complexity of satisfiability problems
STOC '78 Proceedings of the tenth annual ACM symposium on Theory of computing
Answering Regular Path Queries Using Views
ICDE '00 Proceedings of the 16th International Conference on Data Engineering
A Web Odyssey: from Codd to XML
PODS '01 Proceedings of the twentieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Data integration: a theoretical perspective
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Description Logics for Information Integration
Computational Logic: Logic Programming and Beyond, Essays in Honour of Robert A. Kowalski, Part II
Accessing Data Integration Systems through Conceptual Schemas
ER '01 Proceedings of the 20th International Conference on Conceptual Modeling: Conceptual Modeling
View-Based Query Answering and Query Containment over Semistructured Data
DBPL '01 Revised Papers from the 8th International Workshop on Database Programming Languages
Data Integration Needs Reasoning
LPNMR '01 Proceedings of the 6th International Conference on Logic Programming and Nonmonotonic Reasoning
On the Expressive Power of Data Integration Systems
ER '02 Proceedings of the 21st International Conference on Conceptual Modeling
Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
PCK50 Proceedings of the Paris C. Kanellakis memorial workshop on Principles of computing & knowledge: Paris C. Kanellakis memorial workshop on the occasion of his 50th birthday
On the content of materialized aggregate views
Journal of Computer and System Sciences - Special issue on PODS 2000
Querying multidimensional data
Multidimensional databases
Reasoning on regular path queries
ACM SIGMOD Record
Answering queries using views: A KRDB perspective for the semantic Web
ACM Transactions on Internet Technology (TOIT)
Distributed evaluation of generalized path queries
Proceedings of the 2005 ACM symposium on Applied computing
Data integration: a logic-based perspective
AI Magazine - Special issue on semantic integration
Regular path queries under approximate semantics
Annals of Mathematics and Artificial Intelligence
View-based query processing: On the relationship between rewriting, answering and losslessness
Theoretical Computer Science
Towards practically feasible answering of regular path queries in lav data integration
Proceedings of the sixteenth ACM conference on Conference on information and knowledge management
Preferential Regular Path Queries
Fundamenta Informaticae
Certain answers and rewritings for local regular path queries on graph-structured data
Proceedings of the Fourteenth International Database Engineering & Applications Symposium
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
View-based query answering in Description Logics: Semantics and complexity
Journal of Computer and System Sciences
View-based query processing: on the relationship between rewriting, answering and losslessness
ICDT'05 Proceedings of the 10th international conference on Database Theory
Integrating and exchanging XML data using ontologies
Journal on Data Semantics VI
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
Preferential Regular Path Queries
Fundamenta Informaticae
Query processing under GLAV mappings for relational and graph databases
Proceedings of the VLDB Endowment
Spanners: a formal framework for information extraction
Proceedings of the 32nd symposium on Principles of database systems
Querying Regular Graph Patterns
Journal of the ACM (JACM)
Why is it Hard to Obtain a Dichotomy for Consistent Query Answering?
LICS '13 Proceedings of the 2013 28th Annual ACM/IEEE Symposium on Logic in Computer Science
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View-based query processing requires answering a query posed to a database only based on the information on a set of views, which are again queries over the same database. This problem is relevant in many aspects of database management, and has been addressed by means of two basic approaches, namely, query rewriting and query answering. In the former approach, one tries to compute a rewriting of the query in terms of the views, whereas in the latter, one aims at directly answering the query based on the view extensions. We study view-based query processing for the case of regular-path queries, which are the basic querying mechanisms for the emergent field of semi-structured data. Based on recent results, we first show that a rewriting is in general a co-NP function wrt to the size of view extensions. Hence, the problem arises of characterizing, which instances of the problem admit a rewriting that is PTIME. A second contribution of the work is to establish a tight connection between view-based query answering and constraint-satisfaction problems, which allows us to show that the above characterization is going to be difficult. As a third contribution of our work, we present two methods for computing PTIME rewritings of specific forms. The first method, which is based on the established connection with constraint-satisfaction problems, gives us rewritings expressed in Datalog with a fixed number of variables. The second method, based on automata-theoretic techniques, gives us rewritings that are formulated as unions of conjunctive regular-path queries with a fixed number of variables.