C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proc. of the 16th ACM Symp. on Principles of Database Systems (PODS'97), pages 99--108, 1997.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....to the original query (i.e. denote the same set of instances) Nevertheless, often this is not possible. Therefore, a query Figure 1: An example of information sources. reformulation contained in (instead of equivalent to) the original query is considered adequate (see for example [Ullman, 1997; Beeri et al. 1997] Furthermore, when a description logic (e.g. Borgida and Patel Schneider, 1994] is used as data modeling and query language (e.g. Beeri et al. 1997; Kirk et al. 1995; Ullman, 1997] the problem of query containment corresponds to the subsumption problem. There are two basic approaches ....

....sources. reformulation contained in (instead of equivalent to) the original query is considered adequate (see for example [Ullman, 1997; Beeri et al. 1997] Furthermore, when a description logic (e.g. Borgida and Patel Schneider, 1994] is used as data modeling and query language (e.g. [Beeri et al. 1997; Kirk et al. 1995; Ullman, 1997] the problem of query containment corresponds to the subsumption problem. There are two basic approaches to intelligent information integration: the procedural approach and the declarative approach. In the procedural approach (e.g. TSIMMIS [GarciaMolina et ....

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C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting Queries Using Views in Description Logics. In Proc. of the 16th ACM Symposium on Principles of Database Systems (PODS), pages 99--108, New York, NY, May 12--14, Tucson, Arizona 1997. ACM Press.

....to be EXPTIME complete [12, 7] Containment among recursive and nonrecursive datalog queries is also studied in [10] The problem of answering queries using views has been studied in many papers. Table 1 summarizes the results presented in this paper, and other known results in the literature. [5, 6] deal with the problem of answering CQs over description logics using views expressed in description logics. On one hand, description logics are more expressive than CQACs. Therefore, the result that datalog may be necessary to rewrite queries using views that have nondistinguished variables ....

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In PODS, pages 99-108. ACM Press, 1997.

....problems that are contained by the new request can be used as solutions for the new request. In particular, the closest to the new request the retrieved cases are, the best the solutions are. This drives us to the notion of problems maximally contained in the new request (for more details to see [4,15,16,18]) c) When the peer agent experience does not help, a peer agent interacts with other peers. This approach allows the peer to dynamically update its acquaintances (i.e. knowledge about peers past problems) and therefore to take into account changes in information sources and peer s complex ....

.... assume that another dermatologist s peer agent (PA(DE2) owns the case Ck (Figure 5 6) In particular, with respect to the Example 5 3, a2 of Ci is not considered similar to rj of Cj anymore, because, each peer agent calculates the similarity by a containment algorithm (for more details refer to [4,15,16,18]) Under these assumptions, each time the dermatologist (DE) performs a patient s visit in which both cholesterol and blood pressure parameters are wrong (i.e. out of normal ranges) a system failure occurs. Namely, dermatologist s peer agent (PA(DE) Example 5 3) is not able to internally satisfy ....

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting Queries Using Views in Description Logics. In Proceedings of the 16th ACM Symposium on Principles of Database Systems (PODS), Tucson, Arizona 1997.

.... Y ) 1) s 2 (P; L) conference(P; C) year(P; Y ) location(C; Y; L) 2) If we want to know the location where PODS89 was held, we can pose the global query Q : ans(L) location(pods; 1989; L) and we could use the following It is also possible to specify this mapping using description logics [5]. query plan to answer it: ans(L) s 1 (P; pods; 1989) s 2 (P; L) This plan proceeds as follows. It rst nds some paper presented at PODS89 using source s 1 , and then nds the location of the conference at which this paper was presented using source s 2 . This plan is correct because every ....

Beeri, C.; Levy, A. and Rousset, M. Rewriting Queries using Views in Description Logics. In Proceedings of the ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems (PODS'97), 1997, pp.

....and other known results in the literature. Please see Table 2 for the notations. 36] studied conjunctive queries with arithmetic comparisons in the framework of nding whether a conjunctive query always produces an empty relation on database instances satisfying a given set of constraints. [5, 6] deal with the problem of answering CQs over description logics using views expressed in description logics. However, the di erence in expressiveness of description logics and the fact that it allows only unary or binary predicates make their problem di erent from the one of conjunctive queries ....

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In PODS, pages 99-108. ACM Press, 1997.

....in the last years. Several papers investigate query rewriting for the case of conjunctive queries (with or without arithmetic comparisons) 25; 28] disjunctive views [5] queries with aggregates [30; 15] recursive queries and nonrecursive views [16] queries expressed in Description Logics [6], regular path queries [10] and in the presence of integrity constraints [22; 17] Rewriting techniques for query optimization are described, for example, in [13; 4; 31] and in [19; 26; 27] for the case of path queries in semistructured data. A comprehensive framework for view based query ....

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proc. of the 16th ACM SIGACT SIGMOD SIGART Sym. on Principles of Database Systems (PODS'97), pages 99-108, 1997.

....it with AV , we obtain a 1NFA A :Q( t) V having the following property. Theorem 6 Let V be a set of C2RPQ c views, Q a C2RPQ c of arity n, t an n tuple of proper constants, and A :Q( t) V the 1NFA constructed above. Then, t 2 cert(Q; V) if and only if A :Q( t) V is empty. Theorem 7 QA and QC for C2RPQ c s are EXPSPACE complete. Proof. The lower bound for QC follows from EXPSPACE hardness of QC for C2RPQ c s without contstants and inverse, shown in [ 16 ] By Theorem 2 we obtain the same lower bound for QA. For the upper bound for QA, we appeal to the construction ....

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proc. of the 16th ACM SIGACT SIGMOD SIGART Symp. on Principles of Database Systems (PODS'97), pages 99-108, 1997.

....is to exploit all possible information, in particular the view extensions, to compute the answer to the query. In the last years a large number of results have been reported for both problems. Query rewriting has been studied under different assumptions on the form of the queries and views in [34, 38, 42, 6, 19, 7, 28, 20, 17, 27]. Rewriting techniques for query optimization are described, for example, in [16, 5, 43, 23, 35, 36] A comprehensive framework for view based query answering, as well as several interesting results, are presented in [2, 26] In [11, 13, 15] view based query processing has been studied for the ....

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proc. of the 16th ACM SIGACT SIGMOD SIGART Sym. on Principles of Database Systems (PODS'97), pages 99--108, 1997.

....Nevertheless, often this is not possible. As a consequence, in informationintegration applications, query] containment appears to be more fundamental than equivalence [34] Query containment has been related to information integration via an approach called synthesizing queries from views [36, 9, 34, 3, 17]. According to this approach, a query reformulation problem becomes the problem of finding a solution (in terms of views) that must be contained in the original query. Related to the declarative approach is the use of description logics [5, 4, 6] see Appendix A) as a data modeling language and ....

....a solution (in terms of views) that must be contained in the original query. Related to the declarative approach is the use of description logics [5, 4, 6] see Appendix A) as a data modeling language and as a query language. This is the approach followed by several authors, see for example [2, 3, 7, 24, 34]. Indeed, description logics offer an interesting tradeoff between complexity and expressive power. In this perspective, it is worth to notice that the problem of query containment corresponds to the subsumption problem. Subsumption is a tractable problem for most of the description logics [6, 4] ....

[Article contains additional citation context not shown here]

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting Queries Using Views in Description Logics. In Proc. of the 16th ACM Symposium on Principles of Database Systems (PODS), pages 99-- 108, New York, NY, May 12--14, Tucson, Arizona 1997. ACM Press.

....such a reformulation should be equivalent to the original query (i.e. it should denote the same set of instances) Nevertheless, often this is not possible. Therefore, a query reformulation contained in (instead of equivalent to) the original query is considered adequate (see for example [9, 2]) Furthermore, when a description logic [3] is used as data modeling and query language (e.g. 2, 6, 9] the problem of query containment corresponds to the subsumption problem. In the declarative approach to intelligent information integration (e.g. SIMS [1] Information Manifold [6] and ....

....same set of instances) Nevertheless, often this is not possible. Therefore, a query reformulation contained in (instead of equivalent to) the original query is considered adequate (see for example [9, 2] Furthermore, when a description logic [3] is used as data modeling and query language (e.g. [2, 6, 9]) the problem of query containment corresponds to the subsumption problem. In the declarative approach to intelligent information integration (e.g. SIMS [1] Information Manifold [6] and Infomaster [5] mediators use suitable mechanisms to rewrite queries according to source descriptions ....

[Article contains additional citation context not shown here]

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting Queries Using Views in Description Logics. In Proc. of the 16th ACM Symposium on Principles of Database Systems (PODS), pages 99-108, New York, NY, May 12-14, Tucson, Arizona 1997. ACM Press.

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Catriel Beeri, Alon Y.Levy and Marie-Christine Rousset. Rewriting Queries Using Views in Description Logics. In Proceedings of PODS'97, 1997.

....q or one of its equivalent restriction is a tree query. Sketch of proof: The full proof is given in [1] It is based on the above proof, and on the fact that a unique completion is produced by the standard completion calculus in ALE and by the non standard completion calculus in ALN introduced in [4]. Since C j q is equivalent to C(X) j q(X) there exists two mappings ff 1 and ff 2 from the clash free completion SC of C(X) to the clash free completion Sq of CJ (X; Y ) for the former and from the clash free completion Sq of CJ (X; Y ) to the clash free completion SC of C(X) for the latter, ....

C. Beeri, A. Y. Levy, and M-C. Rousset, `Rewriting queries using views in description logics', in Proceedings of PODS 97.

No context found.

C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proc. of the 16th ACM Symp. on Principles of Database Systems (PODS'97), pages 99--108, 1997.

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C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems, pages 99--108, 1997.

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C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proceedings of PODS-97, pages 99--108, 1997.

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C. Beeri, A.Y. Levy, and M-C. Rousset. Rewriting Queries Using Views in Description Logics. In ACM PODS , New York, USA, pages 99--108, Apr. 1997.

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Catriel Beeri, Alon Y. Levy, and Marie-Christine Rousset. Rewriting queries using views in description logics. In Proceedings of the Sixteenth ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, PODS '97, pages 99 -- 108, Tucson, AZ, May 1997.

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C. Beeri, A.Y. Levy, and M-C. Rousset. Rewriting Queries Using Views in Description Logics. In L. Yuan, editor, Proc. of the ACM PODS , New York, USA, pages 99-108, Apr. 1997.

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Catriel Beeri, Alon Y. Levy, and Marie-Christine Rousset. Rewriting queries using views in description logics. In Proc. of the 16th ACM SIGACT SIGMOD SIGART Symp. on Principles of Database Systems (PODS'97), pages 99-108, 1997.

No context found.

Catriel Beeri, Alon Y. Levy, and Marie-Christine Rousset. Rewriting queries using views in description logics. In Proc. of PODS, pages 99-108, Tucson, Arizona., 1997.

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Catriel Beeri, Alon Y. Levy, and Marie-Christine Rousset. Rewriting queries using views in description logics. In Proc. of the 16th ACM SIGACT SIGMOD SIGART Symp. on Principles of Database Systems (PODS'97), pages 99-108, 1997.

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C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proceedings of the Sixteenth ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, page 99108, Tucson, AZ, 1997. ACM Press.

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C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. pages 99--108, Tucson, Arizona., 1997.

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C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proc. of PODS, pages 99-108, Tucson, Arizona., 1997.

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--138, 1998. BLR97. C. Beeri, A. Y. Levy, and M.-C. Rousset. Rewriting queries using views in description logics. In Proc. of the 16th ACM SIGACT SIGMOD SIGART Symp. on Principles of Database Systems (PODS'97), pages

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