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Query Relaxation for Star Queries on RDF [chapter]

Hai Huang, Chengfei Liu
2010 Lecture Notes in Computer Science  
Query relaxation is an important problem for querying RDF data flexibly. The previous work mainly uses ontology information for relaxing user queries.  ...  The similarity of a relaxed query to the original query is measured based on the difference of their estimated results.  ...  The techniques of approximate XML query matching are mainly based on structure relaxation and can not be applied to query relaxation on RDF data.  ... 
doi:10.1007/978-3-642-17616-6_34 fatcat:lrtgxlw5hjc5niemjmlk5pssne

Synthetizing RDF Query Answers from Multiple Documents [chapter]

Adrian Tanasescu, Mohand-Said Hacid
2006 Lecture Notes in Computer Science  
In this paper we propose a framework that provides better, more complete answering to RDF queries than classical answering mechanisms.  ...  This framework provides a way to combine several RDF documents in order to compute a more complete answer to a given query.  ...  As a second preliminary phase, we compute an abstraction tree that will avoid processing the query on the entire RDF documents database. a. Similarity of RDF documents.  ... 
doi:10.1007/11915034_6 fatcat:g47wsxpxuba5zegm4hps2ckhoa

An Evolutionary Perspective on Approximate RDF Query Answering [chapter]

Christophe Guéret, Eyal Oren, Stefan Schlobach, Martijn Schut
2008 Lecture Notes in Computer Science  
RDF is increasingly being used to represent large amounts of data on the Web. Current query evaluation strategies for RDF are inspired by databases, assuming perfect answers on finite repositories.  ...  Our technique supports approximate answers with "anytime" behaviour. We present scalability results and next steps for improvement.  ...  Evolutionary RDF querying Existing RDF stores such as Sesame [6] or YARS [17] mostly employ standard database techniques for query answering.  ... 
doi:10.1007/978-3-540-87993-0_18 fatcat:pvaymijwpzbtjipsqio47tglla

Cooperative Query Answering for RDF [chapter]

Adrian Tanasescu
2005 Lecture Notes in Computer Science  
This transformation allows to compute an ordering on resources and thus provide better answering mechanisms when querying RDF.  ...  Most work on querying RDF has concentrated on the use of logic programming evaluation techniques and SQL extensions.  ...  Furthermore, queries formulated on RDF documents may not provide satisfying answers. Nevertheless, very often, several RDF documents can contribute together to deliver an exact or approximate answer.  ... 
doi:10.1007/11425274_55 fatcat:eftgbmlds5bkbajpzgvcp2vxx4

Anytime Query Answering in RDF through Evolutionary Algorithms [chapter]

Eyal Oren, Christophe Guéret, Stefan Schlobach
2008 Lecture Notes in Computer Science  
We present a technique for answering queries over RDF data through an evolutionary search algorithm, using fingerprinting and Bloom filters for rapid approximate evaluation of generated solutions.  ...  Our evolutionary approach has several advantages compared to traditional databasestyle query answering.  ...  We also discuss existing approaches for querying of RDF data, mostly based on database techniques, and related work in approximate query answering.  ... 
doi:10.1007/978-3-540-88564-1_7 fatcat:dblgrch33jbudewxhtnkknenea

Scaling RDF with Time

Andrea Pugliese, Octavian Udrea, V. S. Subrahmanian
2008 Proceeding of the 17th international conference on World Wide Web - WWW '08  
More importantly, tGRIN can answer queries three to six times faster for average query graph patterns and five to ten times faster for complex queries than these systems.  ...  As a consequence, efforts have been made to annotate RDF triples with "valid time" intervals. However, to date, no proposals exist for efficient indexing of such temporal RDF databases.  ...  On average, answering a query was approximately 19.2% faster for the normalized version.  ... 
doi:10.1145/1367497.1367579 dblp:conf/www/PuglieseUS08 fatcat:2epp55kvsbfi7bnnbgqxx2z72a

DOGMA: A Disk-Oriented Graph Matching Algorithm for RDF Databases [chapter]

Matthias Bröcheler, Andrea Pugliese, V. S. Subrahmanian
2009 Lecture Notes in Computer Science  
In this paper, we first propose the DOGMA index for fast subgraph matching on disk and then develop a basic algorithm to answer queries over this index.  ...  As RDF databases increase in size to approach tens of millions of triples, and as sophisticated graph matching queries expressible in languages like SPARQL become increasingly important, scalability becomes  ...  This assumption clearly does not hold for RDF data. Furthermore, there is a lot work on approximate query answering over graph datasets in the bioinformatics community [22] .  ... 
doi:10.1007/978-3-642-04930-9_7 fatcat:myg3xhd46vbfveqlo7gmkthb4m

An Approach to RDF(S) Query, Manipulation and Inference on Databases [chapter]

Jing Lu, Yong Yu, Kewei Tu, Chenxi Lin, Lei Zhang
2005 Lecture Notes in Computer Science  
Specifically, RDF(S) inference is done on the database in advance instead of on the fly, so that the query efficiency is maximized.  ...  In this paper we propose an approach to the storage, query, manipulation and inference of large RDF(S) data on top of relational databases.  ...  When answering queries, performing the inference on the fly is time consuming.  ... 
doi:10.1007/11563952_16 fatcat:5uszr2jsybesvezct2hdy5qzsu

TrOWL: Tractable OWL 2 Reasoning Infrastructure [chapter]

Edward Thomas, Jeff Z. Pan, Yuan Ren
2010 Lecture Notes in Computer Science  
Tools exist to reason over these ontologies and to answer queries over them, but there are no large scale infrastructures for storing, reasoning, and querying ontologies on a scale that would be useful  ...  We present the TrOWL infrastructure for transforming, reasoning, and querying OWL2 ontologies which uses novel techniques such as Quality Guaranteed Approximations and Forgetting to achieve this goal.  ...  In particular, we utilise a Semantic Approximation [7] to transform OWL2-DL ontologies into OWL2-QL for conjunctive query answering, and a syntactic approximation from OWL2 to OWL2-EL for TBox reasoning  ... 
doi:10.1007/978-3-642-13489-0_38 fatcat:5zf3fzq77rc5hj7n2krlxdbbam

Certain Answers for SPARQL with Blank Nodes [chapter]

Daniel Hernández, Claudio Gutierrez, Aidan Hogan
2018 Lecture Notes in Computer Science  
We thus explore the feasibility of an alternative SPARQL semantics based on certain answers.  ...  database setting for a core fragment of SPARQL.  ...  Acknowledgements The work was also supported by the Millennium Institute for Foundational Research on Data (IMFD) and by Fondecyt Grant No. 1181896.  ... 
doi:10.1007/978-3-030-00671-6_20 fatcat:imtlfngijzaqtj2fml6cmno6ay

Practical and effective IR-style keyword search over semantic web

Xiaomin Ning, Hai Jin, Weijia Jia, Pingpeng Yuan
2009 Information Processing & Management  
In addition, the answer is minimal because any proper subgraph can not be an answer to the query. We provide an approximation algorithm to retrieve these answers efficiently.  ...  In this model, an answer to a keyword query is a connected subgraph that contains all the query keywords.  ...  Trees connecting nodes that contain the query keywords are returned as answers to a keyword query. This model based on database graphs is similar to ours in some degree.  ... 
doi:10.1016/j.ipm.2008.12.005 fatcat:ygzah23t5vdbpp5ivksv67zqaa

A similarity measure for approximate querying over RDF data

Roberto De Virgilio, Antonio Maccioni, Riccardo Torlone
2013 Proceedings of the Joint EDBT/ICDT 2013 Workshops on - EDBT '13  
Approximate query answering relies on a similarity measure that evaluates the relevance, for a given query, of a set of data extracted from the underlying database.  ...  In order to show the feasibility of our approach, we have used such similarity measure in a technique for approximate query answering.  ...  We exploit score to define an algorithm for approximate query answering over RDF.  ... 
doi:10.1145/2457317.2457352 dblp:conf/edbt/VirgilioMT13 fatcat:gknpd3wit5gmncwcqjwmh27t4a

Efficient and scalable processing of frequent SPARQL queries

Rajasekhar Velamuri, P. Sreenivasa Kumar
2013 International Conference on Management of Data  
The number of triples currently published on the web is approximately 62 billion from 870 datasets [4]. We need frameworks that can query RDF data efficiently when the data sizes scale up.  ...  We propose a framework which can run on the scale of billions of triples and answers the frequent SPARQL [7] queries in a reasonable amount of time.  ...  are stored on the local RDF-3X database.  ... 
dblp:conf/comad/VelamuriK13 fatcat:m36dz3223vayblava2eimxfcqq

Relaxed Regular Path Queries in Lightweight DLs (Extended Abstract)

Oliver Fernández Gil, Anni-Yasmin Turhan
2020 International Workshop on Description Logics  
There is prior work on the simple case of instance queries [5] and on C2RPQs in the restricted setting of acyclic ontologies using RDFs schema [12] or nongradual variants of conjunctive queries [11  ...  On the other hand, we are investigating if the approximation mechanism allows to simulate more difficult query answering problems, like for instance, answering nested 2RPQs which is ExpTime-hard in both  ... 
dblp:conf/dlog/GilT20 fatcat:eyow2lqcpvfini3rbrmzxc3zdi

Database Foundations for Scalable RDF Processing [chapter]

Katja Hose, Ralf Schenkel, Martin Theobald, Gerhard Weikum
2011 Lecture Notes in Computer Science  
As more and more data is provided in RDF format, storing huge amounts of RDF data and efficiently processing queries on such data is becoming increasingly important.  ...  We cover search engines as well as federated query processing, highlight differences to classic federated database systems, and discuss efficient techniques for distributed query processing in general  ...  However, the problem of answering queries based on data provided by multiple sources has been known in the database community since the 80s.  ... 
doi:10.1007/978-3-642-23032-5_4 fatcat:5owq3argizaj3epzu4yhuuxc6i
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