T. Soininen, E. Gelle, and I. Niemela. A xpoint denition of dynamic constraint satisfaction. In Joxan Jaar, editor, Proceedings of the Fifth International Conference on Principles and Practice of Constraint Programming, pages 419-433, Alexandria, Virginia, USA, October 1999. Springer-Verlag.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... computational properties [62] An application of smodels in the planning domain has resulted in performance comparable to and sometimes better than that of other ecient general purpose planners [13] Lastly, it has served as an implementation base for dynamic constraint satisfaction problems [61] and for logic programs with weight constraint rules [47] 2 1.3 A Brief History My work on smodels began in February 1995. For my Master s Thesis [57] I implemented a decision procedure for the stable model semantics. The procedure had arisen during the work of my instructor, Ilkka Niemel a, ....

T. Soininen, E. Gelle, and I. Niemela. A xpoint denition of dynamic constraint satisfaction. In Principles and Practice of Constraint Programming { CP'99, volume 1713 of Lecture Notes in Computer Science, pages 419-433, Alexandria, Virginia, USA, October 1999. SpringerVerlag. Proceedings of the 5th International Conference.

.... by a reduction from the problem of deciding whether a positive disjunctive database has a minimal model containing a given atomic formula which is P 2 complete [1] 4 Generalized DCSPs In order to be able to extend the basic DCSP formalism without an increase in complexity Soininen et al. [9] employ a de nition based on a xed point equation which can handle general disjunctive conditions and default negation. The idea is similar to that used in a semantics for a rule based con guration language [8] Generalized DCSPs allow activity constraints of the following form: c 1 ; c ....

....An assignment A is a solution to a DCSP P = hV ; D; V I ; CC ; CA i i 1. A satis es the constraints in P, 2. the initial variables are active in A, 3. A = cl( C A ; V I ) A ) This de nition coincides with the original one in the case where default negations and disjunctions are not allowed [9]. 42 5 Complexity of Generalized DCSPs In this section we study the complexity of deciding whether a generalized DCSP has a solution under the xed point de nition. First we consider the general case and show its NP completeness and then investigate restricted subclasses of generalized activity ....

T. Soininen, I. Niemela, and E. Gelle. A xpoint denition of dynamic constraint satisfaction. Manuscript, 1999.

....model of the program which in turn gives directly a legal coloring of the graph. In fact, smodels has already been employed in a number of areas including planning [13, 44, 36] model checking [38] reachability analysis [26] product con guration [59, 62, 60] dynamic constraint satisfaction [58], logical cryptanalysis [1, 27] and network security [2] Initially smodels supported only normal logic programs. When working towards applications we have observed that normal rules are inadequate for many interesting domains. They lack expressivity to represent, e.g. choices over subsets as ....

T. Soininen, E. Gelle, and I. Niemela. A xpoint denition of dynamic constraint satisfaction. In Joxan Jaar, editor, Proceedings of the Fifth International Conference on Principles and Practice of Constraint Programming, pages 419-433, Alexandria, Virginia, USA, October 1999. Springer-Verlag.

....The property states roughly that everything in a con guration must be grounded (or justi ed) by the con guration model. This is hard to capture in alternative approaches (see more details in the section on related work) However, we use an extension of normal logic programs (Niemel a, Simons, Soininen 1999; Niemel a Simons 2000) This language extends the propositional rule language of (Soininen Niemel a 1999) to the rst order case and adds constraints on sets of weighted literals to capture cardinality and resource constraints. This facilitates compact modeling based on a rich and practically ....

....the con guration model. This is hard to capture in alternative approaches (see more details in the section on related work) However, we use an extension of normal logic programs (Niemel a, Simons, Soininen 1999; Niemel a Simons 2000) This language extends the propositional rule language of (Soininen Niemel a 1999) to the rst order case and adds constraints on sets of weighted literals to capture cardinality and resource constraints. This facilitates compact modeling based on a rich and practically relevant ontology. The language is implemented in the Smodels system and, hence, a prototype product con ....

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Soininen, T.; Gelle, E.; and Niemela, I. 1999. A xpoint denition of dynamic constraint satisfaction. In Proc. of the 5th International Conf. on Principles and Practice of Constraint Programming, 419-433.

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