A. del Val. Tractable databases: how to make propositional unit resolution complete through compilation. pages 551--561, Bonn, 1994.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....If occurs, we have V ll . In ll . In i.e. the same result of the unit rule. Fact 2.16 The application of DPLLunit rule is an instance of a sequence of tableaux rules dneg and (simp) to formulae in clausal normal form. We know that DPLL unit corresponds to boolean constraint propagation BCP [123, 46, 37] so we also have the following result: Proposition 2.17 The clause A is a logical consequence of a set of clauses U with boolean constraint propagation iff there is a tableau proof with only dneg and simp (restricted to literals) as rules of inference. We can extend these result to the general ....

....[56] this problem has been solved in two possible ways: weakening the om niscience or weakening the logical to make inference tractable. The first approach is based on tractable but incomplete classical inference procedures. For instance, we can use unit resolution as advocated by del Val [46, 47] or boolean constraints propagation by Dalai [36, 37] An alterna tive approach is restricting inferences to a subset of formulae as proposed by Rantala [147] or Dalal 85 Etherington [39] Anyhow, we have a complete procedure for a subset of the language and a sound but incomplete (yet tractable) ....

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A. del Val. Tractable databases: How to make propositional unit resolution complete through compilation. In Proc. of the Jth International Conf. on the Principles of Knowledge Representation and Reasoning (KR-9J), pages 551561. Morgan Kaufmann, Los Altos, 1994.

....acyclic graphs (such as OBDDs) which we show to include a relatively large number of target compilation languages. 1 Introduction Knowledge compilation has emerged recently as a key direction of research for dealing with the computational intractability of general propositional reasoning [9, 5, 2, 20, 33, 32, 25, 14, 12, 30]. According to this direction, a propositional theory is compiled off line into a target language, which is then used on line to answer a large number of queries in polytime. The key motivation behind knowledge compilation is to push as much of the computational overhead into the off line phase, ....

A. del Val. Tractable databases: How to make propositional unit resolution complete through compilation. In Proc. of the 4 th International Conference on Knowledge Representation and Reasoning (KR'94), pages 551--561, 1994.

.... compilation has emerged recently as a key direction of research for dealing with the computational intractability of general propositional reasoning [Darwiche, 1999a; Cadoli and Donini, 1997; Boufkhad et al. 1997; Khardon and Roth, 1997; Selman and Kautz, 1996; Schrag, 1996; Marquis, 1995; del Val, 1994; Dechter and Rish, 1994; Reiter and de Kleer, 1987] According to this direction, a propositional theory is compiled off line into a target language, which is then used on line to answer a large number of queries in polytime. The key motivation behind knowledge compilation is to push as much of ....

A. del Val. Tractable databases: How to make propositional unit resolution complete through compilation. In Proc. of International Conference on Knowledge Representation and Reasoning (KR'94), pages 551-- 561, 1994.

....give an algorithm for computing Sigma lub based on the prime implicate computing of Kean and Tsiknis (Figure 3. 2) Though query evaluation in propositional knowledge bases is an NP complete problem, use of knowledge compilation techniques results in efficient algorithms in practice [29] In [12] del Val gives another knowledge compilation technique based on the notion of prime implicates. 2 A horn clause is a disjunction of literals, containing no more than one positive literal. 46 3.7.2 Assumption based truth maintenance systems A clause management system (CMS) 51] is an extension ....

Alvaro del Val. Tractable databases: How to make propositional unit resolution complete through compilation. In Proceedings of the fourth international conference on principles of knowledge representation and reasoning, pages 551--561, 1994.

....between the space complexity of the compiled knowledge base and the number of queries that can be efficiently processed by this data structure. For example, several authors present anytime methods based on prime implicates generation which are sound but incomplete with respect to exact compilation [7, 13, 15]. Dually, Schrag in [18] proposes a prime implicants generation algorithm which is unsound but complete with respect to exact compilation. An analogous strategy has been proposed by Selman and Kautz in the context of Horn approximation for computing all the greatest lower bounds (GLB) of a ....

....which handles these two approaches and that enables us to specify anytime reasoners. We have stressed on a sound and complete multi modal logic, named ARL, which generalizes and expands in several directions previous methods concerning approximate deduction [2, 5, 17] and anytime compilation [7, 15, 18]. Based on this logic, we have illustrated that the framework integrates several major features: resource bounded reasoning, improvability, dual reasoning and off line processing. We believe that the results reported here are interesting and worth of further investigations. We outline some of ....

A. del Val. Tractable databases: How to make propositional unit resolution complete through compilation. In J. Doyle, E. Sandewall, and P. Torasso, editors, Proceedings of the 4th International Conference on Principles of Knowledge Representation and Reasoning, pages 551--561, Bonn, 1994. Morgan Kaufmann.

....added. Nevertheless, such cases rarely occur in practice and even when they do, using forward chaining on the compiled base is more efficient than 2n satisfiability tests on the initial base. At last, achievement includes some other logical compilations such as the ones concerning unit refutation [Val94]. The difference between unit refutation and forward chaining is that this latter is a production algorithm which computes all the unit consequences in a single run, whereas the former can only check that one literal is a consequence. This paper is devoted to the third solution, the use of ....

Alvaro del Val, Tractable Databases: How to Make Propositional Unit Resolution Complete through Compilation, in the proceedings of KR'94, Bohn 1994, pp 551-561. This article was processed using the L A T E X macro package with LLNCS style

....while still ensuring that every query of interest can be answered in polynomial time. KC may be exact or approximate, depending on whether all queries can be answered tractably, or only a subset thereof (see next section) I have made various contributions to approximate KC [7, 8] and exact KC [6, 11]. Current work is focused on scaling up both types of KC by developing new, more restrictive algorithms. My work on KC is surveyed in e.g. 1, 2] 3 Deduction with restricted query languages The deductive task of nding consequences of KB can be made much more e cient when a well de ned ....

A. del Val. Tractable databases: How to make propositional unit resolution complete through compilation. In KR'94, Proc. 4th Int. Conf. on Principles of Knowledge Representation and Reasoning, pp. 551-561. Morgan Kaufmann, 1994.

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A. del Val. Tractable databases: how to make propositional unit resolution complete through compilation. pages 551--561, Bonn, 1994.

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