Edward P. F. Chan. Containment and minimization of positive conjunctive queries in oodb's. In Proc. of the 11th ACM SIGACT SIGMOD SIGART Symp. on Principles of Database Systems (PODS'92), pages 202-211, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....query containment and constraint satisfaction in AI. Florescu et al. 13] show that containment of conjunctive queries with regular path expressions over semistructured data is decidable, using a form of the chase technique. Under some restrictions they show that the problem is NPcomplete. Chan [7] characterized containment and equivalence of conjunctive queries for OODBs and provided a minimization algorithm for a restricted class, called terminal conjunctive queries. His formulation focuses on type inheritance in OODBs and as such his results are not directly applicable to the problems ....

E. P. F. Chan. Containment and minimization of positive conjunctive queries in OODBs. PODS 1992.

....query containment and constraint satisfaction in AI. Florescu et al. 8] show that containment of conjunctive queries with regular path expressions over semistructured data is decidable, using some form of the chase technique. Under some restrictions they show that the problem is NP complete. Chan [4] characterized containment and equivalence of conjunctive queries for OODBs and provided a minimization algorithm for a restricted class, called terminal conjunctive queries. His formulation focuses on type inheritance in OODBs and as such his results are not directly applicable to the problems ....

E. P. F. Chan. Containment and minimization of positive conjunctive queries in OODBs. PODS 1992.

....semi structured data model, LDAP data model deploys the elegant distinguished name (DN) to express the path expression of entries of LDAP while at the same time keeping the first order semantics. The method of adding semantics of class schema constraints to the query processing first appears in [5] for the object oriented data model. Disjunctions are applied to a single query to generate a set of terminal queries with class information for each object variable in the body of the query. However, the algorithm is more pragmatic and can be applied only for the object oriented data model. Our ....

E. P. F. Chan. Containment and Minimization of Positive Conjunctive Queries in OODB's. In Proceedings of the Eleventh ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems (PODS). ACM Press, 1992.

....is that the specialized condition corresponding to r 1 :Condition GammaE is subsumed by r 2 :Condition GammaE . Query subsumption (also called query containment) has been widely investigated, and algorithms for deciding subsumption among object oriented queries have been proposed [29] [30]. Algorithms for testing subsumption among Chimera formulas have been also developed [31] Subsumption can be easily extended to handle also predicates on past database states, as long as the referred past state is the same state in both formulas 20 . Indeed, old(F ) subsumes old(G) if and only ....

E. Chan, "Containment and Minimization of Positive Conjunctive Queries in OODBs," in Proc. of the Eleventh ACM SIGACTSIGMOD -SIGART Symposium on Principles of Database Systems, 1992, pp. 202--211.

....is NP complete. One interesting special case for which containment is tractable is when the right hand side query has bounded treewidth [25] and, in particular, when it is acyclic. Other papers consider the case of conjunctive query containment in the presence of various types of constraints [5, 28, 20, 40, 41, 12]. Conjunctive RPQs without inverse have been studied in [33] where an EXPSPACE algorithm for query containment in this class is presented. In [16] it is shown that containment for conjunctive two way regular path queries without constants is EXPSPACE complete. The complexity of query containment ....

E. P. F. Chan. Containment and minimization of positive conjunctive queries in oodb's. In Proc. of PODS'92, pages 202--211, 1992.

....query containment and constraint satisfaction in AI. Florescu et al. 8] show that containment of conjunctive queries with regular path expressions over semistructured data is decidable, using some form of the chase technique. Under some restrictions they show that the problem is NP complete. Chan [4] characterized containment and equivalence of conjunctive queries for OODBs and provided a minimization algorithm for a restricted class, called terminal conjunctive queries. His formulation focuses on type inheritance in OODBs and as such his results are not directly applicable to the problems ....

E. P. F. Chan. Containment and minimization of positive conjunctive queries in OODBs. PODS 1992.

.... Sag88, CV92] Several works have considered the extension of containment algorithms for queries involving order [Klu88, vdM92, LS93, ZO93, GSUW94] Queries over bags were considered in [CV93] and modifications of containment algorithms to consider semantics of class hierarchies were considered in [Cha92, LR96]. However, containment and equivalence for query languages for complex objects have not been considered previously. Complex Objects Several query formalisms have been proposed [TF86, OOM87, Col93, BNTW95, AB95] We consider the containment and equivalence problems for a certain subset of the ....

Edward P. Chan. Containment and minimization of positive conjunctive queries in oodb's. In The Proceedings of the Eleventh ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, San Diego, CA., pages 202--211, 1992.

.... integration (see [7] and data warehousing where, in addition to the constraints derived from the source schemas and the global schema, inter schema constraints can be used to specify relationships between objects in di erent schemas (see [4] Query containment have, e.g. been studied in [9, 19, 8, 20, 10]. Calvanese et al. 2] have established a theoretical framework using the logic DLR, 1 presented several (un)decidability results, and described a method for solving the decidable cases using an embedding in the propositional dynamic logic CPDL g [13, 12] The importance of this framework is ....

Edward P. F. Chan. Containment and minimization of positive conjunctive queries in OODB's. In ACM, editor, Proc. of PODS'92, 1992. ACM Press.

....without constraints was shown to be NP complete, and a subsequent analysis identified cycles in queries as the main source of complexity [13] Query containment under different forms of constraints have, e.g. been studied in [23] containment w.r.t. functional and inclusion dependencies) and [11, 24] (containment w.r.t. is a hierarchies) Calvanese et al. 4] have established a theoretical framework using the logic DLR, 1 presented several (un)decidability results, and described a method for solving the decidable cases using an embedding in the propositional dynamic logic CPDL g [17, 15] ....

Edward P. F. Chan. Containment and minimization of positive conjunctive queries in OODB's. In Proc. of PODS'92, pages 202--211. ACM Press, 1992.

....di Ingegneria, Universit a di Modena, Via G. Campi 213 A, I 41100 Modena, Italy. e mail: f dbeneventano, sbergamaschi, csartori g deis.unibo.it generalize it to deductive databases [17, 18, 19, 8] More recently, some efforts have been made to perform semantic query optimization in OODBs [9, 11, 16, 6, 1, 2]. The main point is that OODBs provide a very rich type (class) system able to directly represent a subclass of integrity constraints in the database schema. By exploiting schema information as, for instance, inheritance relations between types (classes) it is possible to perform semantic query ....

Edward P.F. Chan. Containment and minimization of positive conjunctive queries in oodb's. In Principles of Database Systems, pages 202--11. ACM, 1992.

....Neither of these classes comprises the language QL, so that QL concepts can be seen as a naturally occurring class of conjunctive queries with polynomial containment problem. In the work on conjunctive queries no schema information like in our case has been taken into account. Recently, Chan [Cha92] has adapted optimization techniques for conjunctive queries to an object oriented setting. He considered some minimal schema information like subclass relationship and disjointness of classes. Although the containment problem for his language is obviously NP hard, he did not address the question ....

E. P. F. Chan. Containment and minimization of positive conjunctive queries in OODB's. In Proc. of the Eleventh ACM SIGACT-SIGMODSIGART Symposium on Principles of Database Systems, pages 202--211, San Diego, CA, 1992.

....A rule r 0 refines a rule r if the condition of r 0 subsumes the condition of r, restricted to the class of r 0 , and the action of r 0 refines the action of r. Containment among conditions can be tested by exploiting algorithms for deciding subsumption among objectoriented queries [9, 12] 11 . Action refinement basically means that the action of the refined rule must do at least what the action of the original rule does. This means that, for each update in the sequence constituting the action of the original rule there must be a corresponding update in the refined action. ....

E. Chan. Containment and Minimization of Positive Conjunctive Queries in OODBs. In Proc. of the Eleventh ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, pages 202--211, 1992.

....Roma, Italy. Email: cabibbo dis.uniroma1.it. Partially supported by MURST and CNR. z Dept. Math. Computer Sci. University of Antwerp (UIA) Universiteitsplein 1, B 2610 Antwerpen, Belgium. E mail: pareda uia.ac.be x INRIA (Projet VERSO) Domaine de Voluceau, Rocquencourt, B.P. 105, F 78153 Le Chesnay Cedex, France. E mail: vdbuss uia.ac.be. On leave from the University of Antwerp. Research Assistant of the Belgian National Fund for Scientific Research. properties of the receiving object, but may also have side effects. Hence, at the most general level, we can define an update ....

....language based on relational algebra and relational assignment, as an interesting research issue. We like to think of our work as first steps in this direction. It should be noted that for each loops have also been used as a potentially non deterministic construct, e.g. in the work of Qian [17] or in the language SETL [19] In this respect it is also interesting to note that the parallel strategy as a means to provide an alternative deterministic semantics to such constructs is very similar in spirit to the relationally computable semantics of a rule in a non deterministic rule ....

[Article contains additional citation context not shown here]

E.P.F. Chan. Containment and minimization of positive conjunctive queries in OODB's. In Proceedings 11th ACM Symposium on Principles of Database Systems, pages 202--211, 1992.

....which are known not to hold for general recursive Datalog programs [14] Since our data model supports object oriented features, our work is also related to the problem of object oriented query rewriting. Previous work on the problem of containment and equivalence of object oriented queries [9, 31] relies on the existence of a static class hierarchy. 15 Work on the containment of queries on complex objects has been presented most recently in [32] However, 32] considers the problem of query containment and equivalence, while we are solving the query rewriting problem. Furthermore, the ....

E. Chan. Containment and minimization of positive conjunctive queries in OODB's. In Proc. PODS Conf., 1992.

....integrity constraints) and the necessary formalism (in term of satisfiability, provability and inference mechanism) for developing a theory of semantic query optimization. More recently, some efforts have been made to perform semantic query optimization in Object Oriented Database Systems (OODBs) [11, 14, 20, 8]. The main point is that OODBs provide a very rich type (class) system able to directly represent a subclass of integrity constraints in the database schema. By exploiting schema information as, for instance inheritance relations between types (classes) it is possible to perform semantic query ....

Edward P.F. Chan. Containment and minimization of positive conjunctive queries in oodb's. In Principles of Database Systems, pages 202--11. ACM, 1992.

....enforce consistency of a database but also to optimize user queries. During the last decade, many efforts have been made to improve this technique and to generalize it to deductive databases [17, 18, 19, 8] More recently, some efforts have been made to perform semantic query optimization in OODBs [9, 11, 16, 6, 1, 2]. The main point is that OODBs provide a very rich type (class) system able to directly represent a subclass of integrity constraints in the database schema. By exploiting schema information This research has been partially funded by the LOGIDATA project of the National Research Council ....

Edward P.F. Chan. Containment and minimization of positive conjunctive queries in oodb's. In Principles of Database Systems, pages 202--11. ACM, 1992.

.... GammaE subsumes r 1 :Condition GammaE , restricted to be evaluated on the same class and to return the same variables. Query subsumption (also called query containment) has been widely investigated, and algorithms for deciding subsumption among object oriented queries have been proposed [11, 18]. Algorithms for testing subsumption among Chimera formulas have been developed [5] Subsumption can be easily extended to handle also predicates on past database states, as long as the referred past state is the same state in both formulas 21 . Indeed, old(F ) subsumes old(G) if and only if F ....

E. Chan. Containment and Minimization of Positive Conjunctive Queries in OODBs. In Proc. of the Eleventh ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, pages 202--211, 1992.

.... reasonable subclasses shown to be decidable [Ull82] Larger decidable subclasses augment conjunctive queries with negation and disjunction. Several object calculi proposals have defined safety in the context of conjunctive queries with disjunction and restricted forms of negation [S O90a, Cha92] These proposals define a broader range of safe queries, however, more general classes have been identified. The class of evaluable queries as first proposed by Demolombe [Dem81] and later examined by van Gelder and Topor [GT87, GT91] is argued to be the largest decidable subclass of domain ....

E.P.F. Chan. Containment and Minimization of Positive Conjunctive Queries in OODB's. In Proc. of the 11th ACM Symposium on Principles of Database Systems, pages 202--211, June 1992.

....which are known not to hold for arbitrary recursive Datalog programs [DG97] Since our data model supports object oriented features, our work is relevant to the problem of object oriented query rewriting. Previous work on the problem of containment and equivalence of object oriented queries [Cha92, LR96] relies on the existence of a static class hierarchy. 10 Work on the containment of queries on complex objects has been presented most recently in [LS97] However, LS97] considers the problem of query containment and equivalence, while we are solving the query rewriting problem. ....

E.P. Chan. Containment and minimization of positive conjunctive queries in OODB's. In Proc. PODS Conf., 1992.

....Neither of these classes comprises the language QL, so that QL concepts can be seen as a naturally occurring class of conjunctive queries with polynomial containment problem. In all this work on conjunctive queries no schema information like in our case has been taken into account. Recently, Chan [Cha92] has investigated the optimization of conjunctive queries in an object oriented setting. He considered some minimal schema information like subclass relationship and disjointness of classes. Although the containment problem for his language is obviously NP hard, he did not address the question of ....

E. P. F. Chan. Containment and minimization of positive conjunctive queries in OODB's. In Proc. of the Eleventh ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, pages 202--211, San Diego, CA, 1992.

.... reasonable subclasses shown to be decidable [Ull82] Larger decidable subclasses augment conjunctive queries with negation and disjunction. Several object calculi proposals have defined safety in the context of conjunctive queries with disjunction and restricted forms of negation [S O90a, Cha92] These proposals define a broader range of safe queries, however, more general classes have been identified. The class of evaluable queries as first proposed by Demolombre [Dem81] and later examined by Gelder and Topor [GT87, GT91] is argued as being the largest decidable subclass of domain ....

E.P.F. Chan. Containment and Minimization of Positive Conjunctive Queries in OODB's. In Proc. of the 11th ACM Symposium on Principles of Database Systems, pages 202--211, June 1992.

....[34] respectively. Query containment under constraints has also been the subject of several investigations. For example, decidability of conjunctive query containment was investigated in [4] under functional and multi valued dependencies, in [14] under functional and inclusion dependencies, in [9, 28, 30] under constraints representing is a hierarchies and complex objects, and in [17] in the case of constraints represented as Datalog programs. In this paper we address query containment in a setting where: ffl The schema is constituted by concepts (unary relations) and relations as basic elements, ....

Edward P. F. Chan. Containment and minimization of positive conjunctive queries in oodb's. In Proc. of the 11th ACM SIGACT SIGMOD SIGART Sym. on Principles of Database Systems (PODS-92), pages 202-- 211, 1992.

....x and y denote the same object or value. Hence Q is unsatisfiable. 2 In this paper, we propose an object oriented counterpart of the relational conjunctive queries and solve the satisfiability problem for such queries. The result is necessary for the study of containment and minimization problems [10] and is applicable to the area of query optimization in an OODB. Query optimization is traditionally divided into two related components: logical transformation and evaluation plan generation using physical knowledge such as indexes and data clustering. Logical transformation is concerned with ....

Chan, E.P.F., "Containment and Minimization of Positive Conjunctive Queries in OODB's," Proceedings of the 11th ACM Symposium on Principles of Database Systems , 1992, pp. 202-211.

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Chan, E.P.F., "Containment and Minimization of Positive Conjunctive Queries in OODB's," Proceedings of the 11th ACM Symposium on Principles of Database Systems, San Diego, CA, 1992, pp. 202-211.

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Edward P. F. Chan. Containment and minimization of positive conjunctive queries in oodb's. In Proc. of the 11th ACM SIGACT SIGMOD SIGART Symp. on Principles of Database Systems (PODS'92), pages 202-211, 1992.

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