ARENAS, M., BERTOSSI, L., AND CHOMICKI , J. 2000. Specifying and querying database repairs using logic programs with exceptions. In Proceedings of the 4th International Conference on Flexible Query Answering Systems. Springer-Verlag, Warsaw, 27--41.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....order on the reducts of the program, and hence on its candidate answer sets. Minimal elements in this induced partial order are called preferred answer sets. The resulting semantics for ordered programs has applications in several areas. e.g. we show that the minimal repairs of a database D [1] w.r.t. a set of constraints C correspond with the preferred answer sets of an ordered program P (D; C) that can be trivially constructed out of D and C. The remainder of this paper is organized as follows: Section 2 extends the usual answer set semantics to cover also inconsistent programs. In ....

....answer set of P is 2 hard. Corollary 1. The problem of deciding whether, given an arbitrary ordered program P and a literal a, whether a occurs in any proper preferred answer set of P is 2 complete. 5 Repairing Databases Using Ordered Programs We review some definitions from [1], using a simplified notation. Definition 8. A database is a consistent set of literals. A constraint is a set A of literals, to be interpreted as a disjunction, c = a2Aa. The Herbrand base BC of a set of constraints C is defined by BC = c2C B c . A database D is consistent with a set of ....

[Article contains additional citation context not shown here]

Marcelo Arenas, Leopoldo Bertossi, and Jan Chomicki. Specifying and querying database repairs using logic programs with exceptions. In Proceedings of the 4th International Conference on Flexible Query Answering Systems, pages 27--41, Warsaw, Octobre 2000. SpringerVerlag.

....between our approach and the one in [3] concerning repairs : 1) their method does not compute the repair databases; 2) our repairs are more refined in the sense that they are closer to the original database than the one in [3] and (3) our repairs do not eliminate inconsistent information. In [4], the same authors present another method to compute consistent answers in possibly inconsistent databases where repairs are specified in a logic programming formalism. This method can treat a larger class of integrity contraints but does not compute the repairs. In [16, 5, 2] the semantics of ....

Arenas, M., Bertossi, L., Chomicki, J. : Specifying and Querying Database Repairs using Logic Programs with Exceptions. In Proc. 4th International Conference on Flexible Query Aswering Systems, October 2000, Warsaw, Poland, Springer-Verlag.

No context found.

Arenas, M.; Bertossi, L. and Chomicki, J. Specifying and Querying Database Repairs using Logic Programs with Exceptions. In Flexible Query Answering Systems. Recent Developments. H.L. arsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27--41.

....a set of integrity constraints IC and a database instance r, construct a space e#cient representation of all repairs of r w.r.t. IC , and then, use this representation to answer queries. Di#erent representations have been considered in this context: 2.1. Repairs are answer sets of a logic program [4,6,14,15]. The compact representation is the program, and to obtain consistent answers, one runs the program. 2.2. Repairs are some distinguished minimal models of a theory written in annotated predicate logic [8,14] 2.3. Repairs are maximal independent sets in a hypergraph whose nodes are database ....

.....Smith, 3000) M .Stowe, 7000) A specification Spec r may provide new ways of computing CQAs and shed some light on the computational complexity of this problem. 4. 1 Logic Programs We show here how to specify the database repairs of an inconsistent database r by means of a logic program # r [4,6]. To pose and answer a first order query Q(x) a stratified logic program #(Q) plus a new goal query atom G(x) is obtained by a standard methodology [81,1] and the query G(x) is evaluated against the program # r ##(Q) The essential part is the program # r . The first observation is that when a ....

[Article contains additional citation context not shown here]

M. Arenas, L. Bertossi, and J. Chomicki. Specifying and Querying Database Repairs Using Logic Programs with Exceptions. In 4th International Conference on Flexible Query Answering Systems, pp. 27--41. Springer-Verlag, 2000.

....soundness,compless,gf and termination of the transformation are studied, and someclegf# of constraints and queries for which consistent query answers can be computed in PTIME are identi#ed. Representingrepairs asstabl model oflgqx programs with disjunction andclg#fzFW negation has been proposed in [4,17]. Those papers consider computingconsistent answers to #rst order queries (but not to aggregation queries) Notractabl cases beyond those of [3] are identi#ed in [4,17] which is not surprisingin view ofCorolNqg 2. Many further questions suggestthemselfEE First, is itpossibl to identify more ....

....PTIME are identi#ed. Representingrepairs asstabl model oflgqx programs with disjunction andclg#fzFW negation has been proposed in [4,17] Those papers consider computingconsistent answers to #rst order queries (but not to aggregation queries) Notractabl cases beyond those of [3] are identi#ed in [4,17], which is not surprisingin view ofCorolNqg 2. Many further questions suggestthemselfEE First, is itpossibl to identify more tractabl cases and to reduce the degree of the polNEFFgj in thosealseg# identi#ed Second, is itpossibl to use approximation in theintractabl cases The INDEPENDENT ....

M. Arenas, L. Bertossi, J. Chomicki, Specifyingand queryingdatabase repairs usinglg ic programs with exceptions, in: Internat. Conf. onFlffENE Query AnsweringSystems, Springer,BerlFz 2000, pp. 27--41.

....of the consistency of the database. The mechanism presented in [2] has some limitations in terms of the ICs and queries that can handle. Although most of the ICs found in database praxis are covered by the positive cases in [2] the queries are restricted to conjunctions of literals. In [4, 6], a more general methodology based on logic programs with a stable model semantics was introduced. There is a one to one correspondence between the stable models of the logic programs and the database repairs. More general queries could be considered, but ICs were restricted to be binary , i.e. ....

....and contain the annotations as constants that appear as new arguments of the database predicates. We establish a one to one correspondence between the stable models of the program and the repairs of the original database. The programs obtained in this wayare simpler than those presented in in [4, 6, 26] in the sense that only one rule per IC is needed, whereas the latter may lead to an exponential number of rules. The logic programs obtained can be used to retrieve consistent answers to arbitrary FO queries. Some computational experiments with DLV [21] are shown. The methodology for consistent ....

[Article contains additional citation context not shown here]

Arenas, M., Bertossi, L. and Chomicki, J. Specifying and Querying Database Repairs using Logic Programs with Exceptions. In ######## ##### ######### #### ##### ###### ############, H.L. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....the data is still consistent. In [Arenas et al. 1999] consistent data in a single relational database is characterized as the data that is invariant under all minimal restorations of consistency, i.e. true in all repaired versions of the original instance (the repairs) In that paper and others [Arenas et al. 2000; Greco et al. 2001] some mechanisms have been developed for retrieving consistent answer when queries are posed to such an inconsistent database. When independent data sources are integrated, inconsistencies wrt to global ICs are likely to occur, specially when the sources are virtually ....

....the assumption that certain global ICs hold has been treated in [Gryz, 1999; Duschka et al. 2000; Grant et al. 2002; Cali et al. 2002] However, in CQA, we do not assume that global ICs hold. Logic programming specifications of repairs of single relational databases have been presented in [Arenas et al. 2000; Greco et al. 2001; Barcelo et al. 2002] Lembo et al. 2002] considers integration systems under the GAV approach that do not satisfy global key dependencies. There, legal instances are allowed to be more flexible, allowing their computed views to accommodate the satisfaction of the ICs. In ....

Arenas, M.; Bertossi, L. and Chomicki, J. Specifying and Querying Database Repairs Using Logic Programs with Exceptions. In Flexible Query Answering Systems. Recent Developments. H. Larsen et al. (eds.), Springer, 2000, pp. 27--41.

....specify his her own constraints as queries are posed, by means of a new, extra SQL statement or a new option in the usual menu for interacting with the DB. The mechanism presented in [2] for consistent query answering (CQA) has some limitations in terms of the ICs and queries it can handle. In [4], a more general methodology based on logic programs with a stable model semantics was introduced. More general queries could be considered, but ICs were restricted to be binary , i.e. universal with at most two database literals (plus built ins) Independently, a similar methodology based on ....

....logic that specify database repairs as presented in [3, 8] Nevertheless, the programs are classical, as opposed to annotated or paraconsistent logic programs [11, 25] The coherent stable models of the program turn out to correspond to the database repairs. The logic programs introduced in [4, 23] to specify database repairs may contain an exponential number of rules depending on the number of database literals appearing in the ICs. However, the programs presented here contain only a linear number of rules. With this approach we reach two goals. The rst goal consists in obtaining a ....

[Article contains additional citation context not shown here]

Arenas, M.; Bertossi, L. and Chomicki, J. \Specifying and Querying Database Repairs using Logic Programs with Exceptions". In Flexible Query Answering Systems. Recent Developments, H.L. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....of the consistency of the database. The mechanism presented in [2] has some limitations in terms of the ICs and queries that can handle. Although most of the ICs found in database praxis are covered by the positive cases in [2] the queries are restricted to conjunctions of literals. In [4, 6], a more general methodology based on logic programs with a stable model semantics was introduced. There is a one to one correspondence between the stable models of the logic programs and the database repairs. More general queries could be considered, but ICs were restricted to be binary , i.e. ....

....and contain the annotations as constants that appear as new arguments of the database predicates. We establish a one to one correspondence between the stable models of the program and the repairs of the original database. The programs obtained in this way are simpler than those presented in in [4, 6, 26] in the sense that only one rule per IC is needed, whereas the latter may lead to an exponential number of rules. The logic programs obtained can be used to retrieve consistent answers to arbitrary FO queries. Some computational experiments with DLV [21] are shown. The methodology for consistent ....

[Article contains additional citation context not shown here]

Arenas, M., Bertossi, L. and Chomicki, J. Specifying and Querying Database Repairs using Logic Programs with Exceptions. In Flexible Query Answering Systems. Recent Developments, H.L. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....a set of integrity constraints IC and a database instance r, construct a space e#cient representation of all repairs of r w.r.t. IC , an then use this representation to answer queries. Di#erent representations have been considered in this context: 2.1. Repairs are answer sets of a logic program [4,6,15]. The compact representation is the program, and to obtain consistent answers, one runs the program. 2.2. Repairs are some distinguished minimal models of a theory written in annotated predicate logic [8,14] 2.3. Repairs are maximal independent sets in a hypergraph whose nodes are database ....

.....Smith, 3000) M .Stowe, 7000) A specification Spec r may provide new ways of computing CQAs and shed some light on the computational complexity of this problem. 4. 1 Logic programs We show here how to specify the database repairs of an inconsistent database r by means of a logic program # r [4,6]. In order to pose and answer a firstorder query Q(x) a stratified logic program #(Q) plus a new goal query atom G(x) is obtained by a standard methodology [80,1] and the query G(x) is evaluated against the program # r #(Q) The essential part is the program # r . The first observation is ....

[Article contains additional citation context not shown here]

M. Arenas, L. Bertossi, and J. Chomicki. Specifying and Querying Database Repairs Using Logic Programs with Exceptions. In International Conference on Flexible Query Answering Systems, pages 27--41. Springer-Verlag, 2000.

....specify his her own constraints as queries are posed, by means of a new, extra SQL statement or a new option in the usual menu for interacting with the DB. That mechanism presented in [2] for consistent query answering (CQA) has some limitations in terms of the ICs and queries it can handle. In [4], a more general methodology based on logic programs with a stable model semantics was introduced. More general queries could be considered, but ICs were restricted to be binary , i.e. universal with at most two database literals (plus built ins) For CQA we need to deal with all the repairs of ....

....order to answer a query, the better. We have experimented with )V, an implementation of the disjunctive stable model semantics [20] The methodology presented here works for arbitrary first order queries and arbitrary universal ICs, what considerable extends the cases that could be han dled in [2, 4, 3]. We also show how to apply the methodology in the presence of referential integrity constraints [1] 2 Preliminaries 2.1 Database repairs and consistent answers We consider a fixed relational database schema = D, P, B) consisting of a fixed, possibly infinite, database domain D = Cl, c2, ....

[Article contains additional citation context not shown here]

Arenas, M.; Bertossi, L. and Chomicki, J. "Specifying and Querying Database Repairs using Logic Programs with Exceptions". In Flexible Query Answering Systems. Recent Developments, H.L. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....a second order theory. Some work has been done on detecting conditions and developing algorithms for the collapse of a (second order) circumscription to a first order theory [25, 15] The same for collapsing circumscription to logic programs [20] In our case, this would not be surprising. In [2, 22, 6], direct specifications of database repairs by means of logic programs are presented. In our case, there is not much hope in having the circumscription collapse to a first order sentence, qCirc. If this were the case, CQA would be feasible in polynomial time in the size of the database, because ....

....for reasoning about contradictory information which is based on an axiomatization in modal propositional logic. Instead, our approach is based on classical first order logic. Other approaches to consistent query answering based on logic programs with stable model semantics were presented in [2, 6, 22]. They can handle general first order queries with universal ICs. There are many open issues. One of them has to do with the possibility of obtaining from the tableaux for instances and ICs the right residues that can be used to rewrite a query as in [1] The theoretical basis of CQA proposed ....

Arenas, M.; Bertossi, L. and Chomicki, J. Specifying and Querying Database Repairs using Logic Programs with Exceptions. In Flexible Query Answering Systems. Recent Developments, H.L. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.). Springer-Verlag, 2000, pp. 27-41.

....systems. The methodology we have presented here is based on the methodology presented in [3] In consequence, it applies to a limited class of queries and constraints. Other approaches to consistent query answering from a single database are based on logic programs with stable model semantics [4, 6, 11]. They can handle general rst order queries. It would be interesting to explore how the methodology presented there can be integrated with the methodology presented in this paper in order to consistently answer queries posed to global integrated A general solution consists in de ning such a ....

Arenas, M.; Bertossi, L. and Chomicki, J. Specifying and Querying Database Repairs Using Logic Programs with Exceptions. In Flexible Query Answering Systems. Recent Developments. H. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....posed to the original, inconsistent database, gets as (normal) answers the consistent answers to the original query. In this paper, we formally de ne the notion of a consistent answer to a query posed to a global system. This notion is an adapatation of the notion proposed in [3] and used in [4, 6, 11]. We also consider the problem of constructing algorithms for computing consistent answers from such a global system. If we want to derive query plans for retrieving, hopefully all and only, answers to a global query that are consistent wrt the desired, global ICs, we may try to use the approach ....

....constraints. The methodology we have presented here is based on the methodology presented in [3] In consequence, it applies to a limited class of queries and constraints. Other approaches to consistent query answering based on logic programs with stable model semantics were presented in [4, 6, 11]. They can handle general rst order queries in the context of a single relational database. It would be interesting to see how the methodology presented there could be integrated with the methodology presented in this paper to consistently answer queries posed to global integrated systems under ....

Arenas, M.; Bertossi, L. and Chomicki, J. Specifying and Querying Database Repairs using Logic Programs with Exceptions. In Flexible Query Answering Systems. Recent Developments. H.L. arsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....queries. The methodology we have presented here is based in its turn on the methodology presented in [3] In consequence, it applies to a limited class of queries and constraints. Other approaches to consistent query answering based on logic programs with stable model semantics were presented in [4, 7, 12]. They can handle general rst order queries in the context of a stand alone relational database. It would be interesting to see how the methodology presented there could be integrated with the methodology presented in this paper to consistently answer conjunctive queries posed to global ....

Arenas, M.; Bertossi, L. and Chomicki, J. Specifying and Querying Database Repairs using Logic Programs with Exceptions. In Flexible Query Answering Systems. Recent Developments. H.L. arsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....to Q( x) in every minimal repair of DB , that is in every database instance over the same schema that di ers from DB by a minimal (under set inclusion) set of inserted or deleted tuples. That mechanism presented in [2] has some limitations in terms of the ICs and queries it could handle. In [4], a more general methodology based on logic programs with an stable Contact author model semantics was introduced. More general queries could be considered, but ICs were restricted to be binary , i.e. universal with at most two database literals (plus built in formulas) For consistent query ....

....2 we present the basic framework, and in section 6 we draw some conclusions, point to ongoing and future work, and consider related work. The methodology presented here works for arbitrary rst order queries and arbitrary universal ICs, what considerable extends the cases that could be handled in [2, 4, 3]. 2 Preliminaries 2.1 Database repairs and consistent answers In the context of relational databases, we will consider a xed relational schema = D; P [ B) that determines a rst order language. It consists of a xed, possibly in nite, database domain D = fc 1 ; c 2 ; g, a xed set of ....

[Article contains additional citation context not shown here]

Arenas, M.; Bertossi, L. and Chomicki, J. \Specifying and Querying Database Repairs using Logic Programs with Exceptions". In Flexible Query Answering Systems. Recent Developments, H.L. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....minimal repair of DB , that is in every database instance over the same schema that di ers from DB by a minimal (under set inclusion) set of inserted or deleted tuples. That mechanism presented in [Arenas et al. 1999] has some limitations in terms of the ICs and queries that can be handled. In [Arenas et al. 2000b] a more general methodology based on logic programs with an stable model semantics was introduced. More general queries could be considered, but ICs were restricted to be binary , i.e. universal with at most two database literals (plus built in formulas) For consistent query answering we ....

....two pieces of information are mutually inconsistent, we need a logic that does not collapse in the presence of contradictions. A logic like Annotated Predicate Logic (APC) Kifer et al. 1992a] for which a classically inconsistent set of premises can still have a model, is a natural candidate. In [Arenas et al. 2000a] a new declarative semantic framework was introduced for studying the problem of query answering in databases that are inconsistent with integrity constraints. This was done by embedding both the database instance and the integrity constraints into a single theory written in APC , with an ....

[Article contains additional citation context not shown here]

Arenas, M.; Bertossi, L. and Chomicki, J. \Specifying and Querying Database Repairs using Logic Programs with Exceptions". In Flexible Query Answering Systems. Recent Developments, H.L. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

....could specify his her own constraints as queries are posed, by means of a new, extra SQL statement or a new option in the usual menu for interacting with the DB. That mechanism presented in [2] for consistent query answering has some limitations in terms of the ICs and queries it can handle. In [4], a more general methodology based on logic programs with a stable model semantics was introduced. More general queries could be considered, but ICs were restricted to be binary , i.e. universal with at most two database literals (plus built in formulas) For consistent query answering we need ....

....is true of every stable model. For this purpose, an implementation of the disjunctive stable model semantics, like DLV [13] can be used. The methodology presented here works for arbitrary rst order queries and arbitrary universal ICs, what considerable extends the cases that could be handled in [2, 4, 3]. We also show how to apply the methodology in the presence of referential integrity constraints [1] 2 Preliminaries 2.1 Database repairs and consistent answers In the context of relational databases, we will consider a xed relational schema = D; P [ B) that determines a rst order ....

[Article contains additional citation context not shown here]

Arenas, M.; Bertossi, L. and Chomicki, J. \Specifying and Querying Database Repairs using Logic Programs with Exceptions". In Flexible Query Answering Systems. Recent Developments, H.L. Larsen, J. Kacprzyk, S. Zadrozny, H. Christiansen (eds.), Springer, 2000, pp. 27-41.

No context found.

ARENAS, M., BERTOSSI, L., AND CHOMICKI , J. 2000. Specifying and querying database repairs using logic programs with exceptions. In Proceedings of the 4th International Conference on Flexible Query Answering Systems. Springer-Verlag, Warsaw, 27--41.

No context found.

Marcelo Arenas, Leopoldo Bertossi, and Jan Chomicki. Specifying and querying database repairs using logic programs with exceptions. In Proceedings of the 4th International Conference on Flexible Query Answering Systems, pages 27--41, Warsaw, Octobre 2000. SpringerVerlag.

No context found.

M. Arenas, L. Bertossi, and J. Chomicki. Specifying and Querying Database repairs using Logic Programs with Exceptions. In Proceedings International Conference on Flexible Query Answering, pages 27--41, 2000.

No context found.

M. Arenas, L. Bertossi, and J.Chomicki. Specifying and querying database repairs using logic programs with exceptions. In Procs. of the 4th International Conference on Flexible Query Answering Systems, pages 27--41. Springer-Verlag, 2000.

No context found.

Marcelo Arenas, Leopoldo Bertossi, and Jan Chomicki. Specifying and querying database repairs using logic programs with exceptions. In Proceedings of the 4th International Conference on Flexible Query Answering Systems, pages 27--41, Warsaw, Octobre 2000. SpringerVerlag.

No context found.

M. Arenas, L. Bertossi, and J. Chomicki. Specifying and querying database repairs using logic programs with exceptions. In Proceedings of the International Conference on Flexible Query Answering, 2000.

No context found.

M. Arenas, L. E. Bertossi, and J. Chomicki. Specifying and querying database repairs using logic programs with exceptions. In Proc. 4th Int'l Conference on Flexible Query Answering Systems (FQAS 2000), pp. 27--41. Springer, 2000.

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