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Efficient approximations of conjunctive queries

Pablo Barceló, Leonid Libkin, Miguel Romero
2012 Proceedings of the 31st symposium on Principles of Database Systems - PODS '12  
In this paper we study such approximations for conjunctive queries.  ...  When finding exact answers to a query over a large database is infeasible, it is natural to approximate the query by a more efficient one that comes from a class with good bounds on the complexity of query  ...  We thank Wenfei Fan, Claudio Gutierrez, Luc Segoufin, Thomas Schwentick, and the referees of conference versions [6, 7] for their comments.  ... 
doi:10.1145/2213556.2213591 dblp:conf/pods/BarceloLR12 fatcat:t3koqpn5azf6baoduqz3kgbpeq

Efficient Approximations of Conjunctive Queries

Pablo Barceló, Leonid Libkin, Miguel Romero
2014 SIAM journal on computing (Print)  
In this paper we study such approximations for conjunctive queries.  ...  When finding exact answers to a query over a large database is infeasible, it is natural to approximate the query by a more efficient one that comes from a class with good bounds on the complexity of query  ...  We thank Wenfei Fan, Claudio Gutierrez, Luc Segoufin, Thomas Schwentick, and the referees of conference versions [6, 7] for their comments.  ... 
doi:10.1137/130911731 fatcat:ombnpwrj6nd4fjlwma73w4gfum

TrOWL: Tractable OWL 2 Reasoning Infrastructure [chapter]

Edward Thomas, Jeff Z. Pan, Yuan Ren
2010 Lecture Notes in Computer Science  
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.  ...  The Semantic Web movement has led to the publication of thousands of ontologies online. These ontologies present and mediate information and knowledge on the Semantic Web.  ...  We would also like to thank Stuart Taylor, Nophadol Jekjantuk and Yuting Zhao at the University of Aberdeen for their helpful discussion and other contributions.  ... 
doi:10.1007/978-3-642-13489-0_38 fatcat:5zf3fzq77rc5hj7n2krlxdbbam

Query Abduction for ELH Ontologies

Mahsa Chitsaz, Zhe Wang, Kewen Wang
In this paper, we develop a sound and complete algorithm of query abduction for general conjunctive queries in ELH ontologies. This is achieved through ontology approximation and query rewriting.  ...  We evaluated our algorithm over university benchmark ontology and our experimental results show that the system is capable of handling query abduction problems for ontology that has approximately 10 millions  ...  A conjunctive query Q( x) is of the form ∃ y.φ( x, y), where φ is a conjunction of atoms with predicates and terms from N C ∪ N R and N I ∪ N V , respectively.  ... 
doi:10.1609/aaai.v29i1.9717 fatcat:eb37iwmcqre4xbg7po7jqssxge

Scaling Out Sound and Complete Reasoning for Conjunctive Queries on OWL Knowledge Bases

Sambhawa Priya
2015 International Semantic Web Conference  
queries to nodes of the cluster.  ...  The focus of this thesis is to develop a scalable framework to perform sound and complete reasoning on large and expressive data graphs for answering conjunctive queries over a cluster of commodity machines  ...  for answering conjunctive queries efficiently.  ... 
dblp:conf/semweb/Priya15 fatcat:4shbvnicfrhizbd4jijqb3dpa4

Special Issue on the 2018 International Conference on Database Theory

Benny Kimelfeld
2020 Theory of Computing Systems  
Theory of Static Approximations for Conjunctive Queries," by Pablo Barceló, Miguel Romero, and Thomas Zeume, considers the approach of overcoming the intrinsic complexity of conjunctive queries by replacing  ...  the query with a more efficient alternative that constitutes an approximation with theoretical guarantees.  ... 
doi:10.1007/s00224-020-09968-7 fatcat:3pic46fpkbfwxbv3cd7bwizlo4


Pierre Senellart, Asma Souihli
2011 Proceedings of the 2011 international conference on Management of data - SIGMOD '11  
A user chooses between a variety of query answering techniques, both exact and approximate, and observes the running behavior, pros, and cons, of each method, in terms of efficiency, precision of the result  ...  We demonstrate a system for querying probabilistic XML documents with simple XPath queries.  ...  We appeal to these theoretical studies to perform efficient translations, as encoding matches with conjunctions of all events involved simplify the computation and approximation processes.  ... 
doi:10.1145/1989323.1989480 dblp:conf/sigmod/SenellartS11 fatcat:okoyaxoh6nak3ai3ykn3ybbwta

It's Not What Machines Can Learn, It's What We Cannot Teach [article]

Gal Yehuda, Moshe Gabel, Assaf Schuster
2020 arXiv   pre-print
We empirically explore a case study, Conjunctive Query Containment, and show how common data generation techniques generate biased datasets that lead practitioners to over-estimate model accuracy.  ...  Can deep neural networks learn to solve any task, and in particular problems of high complexity?  ...  Conjunctive Query Containment (CQC) is the set of all pairs (p, q) of conjunctive queries such that p(D) ⊆ q(D) for every database D; we denote such pairs by p ⊆ q.  ... 
arXiv:2002.09398v2 fatcat:qtyoeni6crhlnb4pqauh4jaodm

Filtering with Approximate Predicates

Narayanan Shivakumar, Hector Garcia-Molina, Chandra Chekuri
1998 Very Large Data Bases Conference  
We model different types of approximate predicates and their dependencies, we derive expressions for the errors of compound predicates, and we develop query optimization strategies.  ...  In this paper we study the problem of selecting and structuring approximate predicates in order to reduce the cost of processing a user query, while keeping errors within user-specified bounds.  ...  LinearWrapper is more efficient than the doublyexponential Naive Wrapper and the singly-exponential Conjunctive Wrapper since it is linear in the number of approximate predicates.  ... 
dblp:conf/vldb/ShivakumarGC98 fatcat:uv2sff5dcbadtm2mmw47rn2ivy

Approximating Terminological Queries [chapter]

Heiner Stuckenschmidt, Frank van Harmelen
2002 Lecture Notes in Computer Science  
An application of these languages on the World Wide Web, however, is hampered by the limitations of logical reasoning in terms of efficiency and flexibility.  ...  We discuss terminological knowledge and approximate reasoning in general and show the benefits of approximate reasoning using the example of building and maintaining semantic catalogues that can be used  ...  In order to improve the efficiency of this approach, we propose various strategies for approximating answers by relaxing the query expression to a subsuming one that still returns all correct answers but  ... 
doi:10.1007/3-540-36109-x_26 fatcat:csbfujwyprhljfds7q5ycwzc5a

Special issue on best papers of VLDB 2015

Chen Li, Volker Markl
2016 The VLDB journal  
of conjunctive queries.  ...  The authors show that by considering schema information it is possible to generate a minimal set of query plans within a database engine, thus computing the propagation score efficiently.  ...  The authors also introduce a simple method to estimate the selectivity of inequality joins in order to optimize conjunctive queries and multi-way joins.  ... 
doi:10.1007/s00778-016-0450-5 fatcat:bs244b7w6fbflnahsx5cctaqfi

Efficient Query Answering Through Approximation

Edward Thomas, Jeff Z. Pan
2007 International Workshop on Description Logics  
In this poster, we propose to recast the idea of knowledge compilation into approximating OWL DL ontologies with DL-Lite ontologies, against which query answering has only polynomial data complexity.  ...  We identify a useful category of queries for which our approach also guarantees completeness. Furthermore, we paper report on the implementation of our approach in the ONTOSEARCH2 system.  ...  Unlike existing syntactic approximation approach, our approach always guarantees sound answers for conjunctive and disjunctive queries over ontologies.  ... 
dblp:conf/dlog/ThomasP07 fatcat:23h45til3rhiffl5za4mocqf5e

Ranking Approximate Answers to Semantic Web 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, thus including extensions proposed for SPARQL to allow for querying paths using regular expressions.  ...  In these circumstances, it is helpful if the querying system can perform an approximate matching of the user's query to the data and can rank the answers in terms of how closely they match the original  ...  We are interested in developing efficient algorithms which allow for the approximate matching of users' queries on such data, with the answers to queries being returned to users in ranked order.  ... 
doi:10.1007/978-3-642-02121-3_22 fatcat:dutoouvmovcfnd6imkeaxudvsa

On Constrained Open-World Probabilistic Databases [article]

Tal Friedman, Guy Van den Broeck
2019 arXiv   pre-print
We provide an algorithm for one class of queries, and establish a basic hardness result for another. Finally, we propose an efficient and tight approximation for a large class of queries.  ...  One approach is to use a probabilistic database, a model with strong assumptions that allow for efficiently answering many interesting queries.  ...  construct an efficient approximation.  ... 
arXiv:1902.10677v2 fatcat:k4sytuw64jhc3n34h7tf7tkbhy

Efficient Upper Bound Computation of Query Answers in Expressive Description Logics

Yujiao Zhou, Bernardo Cuenca Grau, Ian Horrocks
2012 International Workshop on Description Logics  
Queries. A conjunctive query (CQ), or simply a query, is a formula Q(x) of the form ∃y.ϕ(x, y), where ϕ(x, y) is a conjunction of atoms.  ...  The technique we use is to approximate T to give an ontology T that is strictly "stronger" that T (i.e., T |= T ), and that is within a fragment for which query answers can be efficiently computed.  ... 
dblp:conf/dlog/ZhouGH12 fatcat:klybpm4scjhc7mw3vajnegoyoi
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