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Query containment for conjunctive queries with regular expressions

Daniela Florescu, Alon Levy, Dan Suciu
1998 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems - PODS '98  
For a restricted class of conjunctive queries with regular path exrepssions we s h o w that containment and equivalence are NP-complete.  ...  We s h o w that these problems are decidable for conjunctive queries with regular path expressions.  ...  Conclusions We have discussed query containment for the query language StruQL 0 , consisting of conjunctive queries with regular path expressions, from two angles: a semantic angle, where we s h o wed  ... 
doi:10.1145/275487.275503 dblp:conf/pods/FlorescuLS98 fatcat:kehgwth2efhlhpj4noi5poanhq

Finding Top-k Approximate Answers to Path Queries [chapter]

Carlos A. Hurtado, Alexandra Poulovassilis, Peter T. Wood
2009 Lecture Notes in Computer Science  
The query language we adopt comprises conjunctions of regular path queries, allowing path variables to appear in the bodies and the heads of rules, so that paths can be returned to the user.  ...  We show that the top-k approximate answers can be returned in polynomial time in the size of the database graph and the query. matching of conjunctive regular path queries [6], where each X i and Y i ,  ...  In Section 2, we consider first the case of computing approximate answers for ERP queries containing only one conjunct.  ... 
doi:10.1007/978-3-642-04957-6_40 fatcat:y5ujzl7uk5gwppiacohdq4rmbe

Conjunctive Regular Path Queries with String Variables [article]

Markus L. Schmid
2019 arXiv   pre-print
We introduce the class CXRPQ of conjunctive xregex path queries, which are obtained from conjunctive regular path queries (CRPQs) by adding string variables (also called backreferences) as found in practical  ...  In terms of expressive power, we compare the CXRPQ-fragments with CRPQs and unions of CRPQs, and with extended conjunctive regular path queries (ECRPQs) and unions of ECRPQs.  ...  General graph patterns labelled by regular expressions are called conjunctive regular path queries (CRPQs).  ... 
arXiv:1912.09326v1 fatcat:uloc7bnqpza4fkhhvs7murniau

A call to regularity

Moshe Y. Vardi
2003 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 - PCK50  
· · l k ∈ L 1 Corollary: Path-Query Containment is • undecidable for context-free path queries • decidable for regular path queries.  ...  regular paths in labeled graphs Research Question: What is the ultimate class of regular queries?  ... 
doi:10.1145/778348.778352 fatcat:36cih6nywvaqdm5wkhgap23i3m

Definability problems for graph query languages

Timos Antonopoulos, Frank Neven, Frédéric Servais
2013 Proceedings of the 16th International Conference on Database Theory - ICDT '13  
In this paper, we consider the definability problem for regular paths and conjunctive regular path queries (CRPQs) over labelled graphs. * We acknowledge the financial support of the Future and Emerging  ...  Given a graph, a relation on its nodes, and a query language Q of interest, we study the Q-definability problem which amounts to deciding whether there exists a query in Q defining precisely the given  ...  Initially, conjunctive regular path queries have been studied mainly from the angle of query containment [9, 17, 14] .  ... 
doi:10.1145/2448496.2448514 dblp:conf/icdt/AntonopoulosNS13 fatcat:csxl5zjws5azfmdh7ncvaaw5ry

Query languages for graph databases

Peter T. Wood
2012 SIGMOD record  
We provide a brief survey of many of the graph query languages that have been proposed, focussing on the core functionality provided in these languages.  ...  We also consider issues such as expressive power and the computational complexity of query evaluation.  ...  Acknowledgements I would like to dedicate this survey to the memory of Alberto Mendelzon, whose insight and vision inspired me to investigate graph query languages some 25 years ago.  ... 
doi:10.1145/2206869.2206879 fatcat:ewen3opekbfyzbv3pnc6h6o7tm

Combining Approximation and Relaxation in Semantic Web Path Queries [chapter]

Alexandra Poulovassilis, Peter T. Wood
2010 Lecture Notes in Computer Science  
The query language we adopt comprises conjunctions of regular path queries, thus including extensions proposed for SPARQL to allow for querying paths using regular expressions.  ...  We develop query relaxation techniques for regular path queries and combine them with query approximation in order to support flexible querying of RDF data when the user lacks knowledge of its full structure  ...  We restrict our query language to that of conjunctive regular path queries [2] .  ... 
doi:10.1007/978-3-642-17746-0_40 fatcat:5uasd74kxfdmnmuelueqvofibi

Containment of Simple Regular Path Queries [article]

Diego Figueira and Adwait Godbole and S. Krishna and Wim Martens and Matthias Niewerth and Tina Trautner
2020 arXiv   pre-print
We study here the containment problem for Conjunctive Regular Path Queries (CRPQs), a navigational query language extensively used in ontology and graph database querying.  ...  We obtain a detailed overview of the complexity of the containment problem, depending on the features used in the regular expressions of the queries, with completeness results for np, pitwo, pspace or  ...  Although much of the work on querying knowledge bases is focused on conjunctive queries, there is often the need to use a simple form of recursion, such as the one provided by regular path queries (RPQ  ... 
arXiv:2003.04411v1 fatcat:chvvu3lmxjdm3ndsavyxca5mw4

Editor's foreword

Pablo Barceló
2013 Journal of computer and system sciences (Print)  
of conjunctive regular path queries (CRPQs) with path comparisons.  ...  The paper "Expressiveness and Static Analysis of Extended Conjunctive Regular Path Queries", by Freydenberger and Schweikardt, studies the containment and equivalence problem for an extension of the class  ...  They prove that this is the case for queries of bounded hyper-treewidth and no existentially quantified variables, and that removing any of these conditions easily leads to intractability.  ... 
doi:10.1016/j.jcss.2013.01.003 fatcat:yu53yrya3vcifnc3ztj4oaj22i

View-based query containment

Diego Calvanese, Giuseppe De Giacomo, Maurizio Lenzerini, Moshe Y. Vardi
2003 Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems - PODS '03  
In particular, for the two settings of conjunctive queries and two-way regular path queries, we provide both techniques and complexity bounds for the different variants of the problem.  ...  Such a form of containment, which we call view-based query containment, is the subject of this paper.  ...  For both settings of conjunctive queries and of two-way regular path queries, we have provided techniques and complexity bounds for the different variants of view-based query containment.  ... 
doi:10.1145/773153.773160 dblp:conf/pods/CalvaneseGLV03 fatcat:awxnuf4p6jbkfdxmmsmv4ddewu

Decidable Containment of Recursive Queries [chapter]

Diego Calvanese, Giuseppe De Giacomo, Moshe Y. Vardi
2002 Lecture Notes in Computer Science  
It is also known that containment between unions of conjunctive two-way regular path queries (UC2RPQs), which are queries used in the context of semistructured data models containing a limited form of  ...  On the other hand, it is known that containment between monadic Datalog queries and between Datalog queries and unions of conjunctive queries are decidable.  ...  We consider unions of conjunctive 2-way regular path queries (UC2RPQs) [34] , which extend regular path queries with the possibility to traverse edges backwards, with conjunctions and variables, and with  ... 
doi:10.1007/3-540-36285-1_22 fatcat:dydffenp6zevbnrk4fn5kgbwi4

Decidable containment of recursive queries

Diego Calvanese, Giuseppe De Giacomo, Moshe Y. Vardi
2005 Theoretical Computer Science  
It is also known that containment between unions of conjunctive two-way regular path queries (UC2RPQs), which are queries used in the context of semistructured data models containing a limited form of  ...  On the other hand, it is known that containment between monadic Datalog queries and between Datalog queries and unions of conjunctive queries are decidable.  ...  We consider unions of conjunctive 2-way regular path queries (UC2RPQs) [34] , which extend regular path queries with the possibility to traverse edges backwards, with conjunctions and variables, and with  ... 
doi:10.1016/j.tcs.2004.10.031 fatcat:73zwqlpqp5d2tja4a3q25cf47q

Query Rewriting under Linear $$\mathcal {EL}$$ Knowledge Bases [chapter]

Mirko M. Dimartino, Andrea Calì, Alexandra Poulovassilis, Peter T. Wood
2016 Lecture Notes in Computer Science  
With the adoption of the recent SPARQL 1.1 standard, RDF databases are capable of directly answering more expressive queries than simple conjunctive queries.  ...  In particular, we show a query answering algorithm that rewrites a given CQ into a conjunctive regular path query (CRPQ) which, evaluated on the given instance, returns the correct answer.  ...  Moreover, in the case of "simple" queries such as atomic queries, our rewriting is expressed as a regular path query, which can be evaluated in NLOGSPACE.  ... 
doi:10.1007/978-3-319-45276-0_6 fatcat:lo3wraypgrfbfl2xtyj24p32zq

Navigating the Maze of Wikidata Query Logs

Angela Bonifati, Wim Martens, Thomas Timm
2019 The World Wide Web Conference on - WWW '19  
Although the usage of Wikidata queries has been the object of recent studies, our analysis of the query traffic reveals interesting and unforeseen findings concerning the usage, types of recursion, and  ...  the shape classification of complex recursive queries.  ...  Apart from simple counting measures on this fragment, we have focused on tailoring property path analysis and shape analysis to these queries, whereas previous work merely looked at conjunctive queries  ... 
doi:10.1145/3308558.3313472 dblp:conf/www/BonifatiMT19 fatcat:yej2ru6c7ne7valoqkqs74f42q

Anatomy of the coupling query in a web warehouse

Sourav S. Bhowmick, Wee Keong Ng, Sanjay Madria, Ee-Peng Lim
2002 Information and Software Technology  
constraints on tag attributes and tagless segment of data, ability to express conjunctive as well as disjunctive query conditions compactly, ability to control execution of a web query and preservation  ...  of the topological structure of hyperlinked documents in the query results.  ...  With the above two types of link components, a link path expression is simple if the path expression contains only a simple link component. Otherwise, it is a regular link path expression.  ... 
doi:10.1016/s0950-5849(02)00051-4 fatcat:i7gl32rulzephfy6metwdd3lu4
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