Molly Wilson and Alan Borning. Extending hierarchical constraint logic programming: Nonmonotonicity and inter-hierarchical comparison. In Proc. of the North American Conference on Logic Programming, pages 3--19, Cleveland, Ohio, 1989.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... 0 e 0 0 ; e n n e 0 n i and he 0 ; e n i he 0 0 ; e 0 n i is true iff an i exists with 0 i n and e i i e 0 i and e j = e 0 j for all j with 0 j i. These structures are closely related to constraint hierarchies including inter hierarchy comparison [Wilson and Borning, 1989] . 2 Defining optimization with such valuations is straight forward. Def. 2 A tuple P = hX; D;C;Si defines a constraint optimization problem (COP) iff X is a set of variables, D is a set of values called initial domain, S = hE; i is a valuation structure, and C is a set of locally defined ....

Molly Wilson and Alan Borning. Extending hierarchical constraint logic programming: Nonmonotonicity and inter-hierarchical comparison. In Proc. of the North American Conference on Logic Programming, pages 3--19, Cleveland, Ohio, 1989.

....in detail by Freuder and Wallace in [8] The underlying (natural) metric simply counts the number of satisfied constraints. The best solutions are those with the smallest number of constraint violations. Hierarchical Constraint Logic Programming (HCLP) was developed by Wilson, Borning et al. [29, 30]) and expresses preferences by employing a constraint hierarchy. Constraints on the highest level of the hierarchy always have to be satisfied. Constraints on lower levels may be violated. The lexicographic ordering of the hierarchy levels ensures that the satisfaction of a more important ....

M. Wilson and A. Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison. In Proceedings of the

....comparators. While the locally better comparators consider each constraint individually, the globally better comparators combine errors of all constraints at a given level using some combining function. Thus, the globally better comparators can be used for inter hierarchy comparison [13], i.e. comparison of solutions to two or more constraint hierarchies. For a regionally better comparator, each constraint at a given level is considered individually (as with a local comparator) but, unlike a local comparator, two solutions that are incomparable at strong levels may still be ....

....are used in Hierarchical Constraint Logic Programming (HCLP) which is an extension of Constraint Logic Programming (CLP) In the original definition of HCLP [4,14] only alternate solutions to one constraint hierarchy are compared and the best solutions are returned. The later extension of HCLP [13] also enables comparison of solutions to more constraint hierarchies arising from different choices of rules in HCLP program. Such comparison, called inter hierarchy comparison (opposite to more common intra hierarchy comparison) rules out non intuitive solutions and, in our opinion, it is closer ....

[Article contains additional citation context not shown here]

Wilson, M., Borning, A., Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison, Tech. Report 89-05-04, Department of Computer Science and Engineering, University of Washington, July 1989

....comparators 3 . While the locally better comparators consider each constraint individually, the globally better comparators combine errors of all constraints at a given level using some combining function. Thus, the globally better comparators can be used for inter hierarchy comparison [22], i.e. comparison of solutions to two or more constraint hierarchies. The theory of constraint hierarchies was developed in [6] and it is also described in [8,22,23] The existence of efficient satisfaction algorithms is another important aspect of constraint hierarchies. Most current ....

....at a given level using some combining function. Thus, the globally better comparators can be used for inter hierarchy comparison [22] i.e. comparison of solutions to two or more constraint hierarchies. The theory of constraint hierarchies was developed in [6] and it is also described in [8,22,23]. The existence of efficient satisfaction algorithms is another important aspect of constraint hierarchies. Most current satisfaction algorithms, in other words constraint hierarchy solvers, can be classified into two groups: algorithms based on refining method and local propagation algorithms. ....

Wilson, M., Borning, A., Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison, Tech. Report 89-05-04, Department of Computer Science and Engineering, University of Washington, July 1989

.... diverse areas as intelligent backtracking in CLP( languages, spatial reasoning [THL91] model based diagnosis [DBB91] disjunctive scheduling and resource allocation [Bak74] electrical enginnering [HMS92] expert systems [Hav92] incremental user interfaces [MS89] and constraint hierarchies [BMMW89, WB89]. The applicability of failure analysis in the above described domains has to be investigated in the future in detail. Chapter 5 Implementation of IBCLP(R) 5.1 Overview of the IBCLP(R) interpreter In this section the experimental implementation of an IBCLP( meta interpreter is presented. The ....

....[BLH94] and [DBB91] do not present any algorithm for finding all conflicting sets of constraints. Having such a procedure can be very useful in other applications especially in implementing intelligent user interfaces [vEOT86] constraint hierarchies and systems with preferences on constraints [BMMW89, WB89]. CHAPTER 5. IMPLEMENTATION OF IBCLP(R) 163 The algorithms 4.8 and 4.9 described in the previous chapter are very expensive to implement in both space and time. Every iteration of the algorithm creates a new copy of the subtableau that contains only slack variables. Another auxiliary data ....

M. Wilson and A. Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison. In Ewing L. Lusk and Ross A. Overbeek, editors, Proceedings of the North American Conference on Logic Programming, pages 3--19, Cleveland, Ohio, USA, 1989.

....comparators. While the locally better comparators consider each constraint individually, the globally better comparators combine errors of all constraints at a given level using some combining function. Thus, the globally better comparators can be used for inter hierarchy comparison [13], i.e. comparison of solutions to two or more constraint hierarchies. The constraint hierarchies are used in Hierarchical Constraint Logic Programming (HCLP) which is an extension of Constraint Logic Programming (CLP) In the original definiton of HCLP [4,14] only alternate solutions to one ....

....are used in Hierarchical Constraint Logic Programming (HCLP) which is an extension of Constraint Logic Programming (CLP) In the original definiton of HCLP [4,14] only alternate solutions to one constraint hierarchy are compared and the best solutions are returned. The later extension of HCLP [13] also enables comparison of solutions to more constraint hierarchies arising from different choices of rules in HCLP program. Such comparison, called inter hierarchy comparison (opposite to more common intra hierarchy comparison) rules out non intuitive solutions and, in our opinion, it is closer ....

[Article contains additional citation context not shown here]

Wilson, M., Borning, A., Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison, Tech. Report 89-05-04, Department of Computer Science and Engineering, University of Washington, July 1989

....finishing implementation of a generalized local propagation [10] algorithm that is at least partially incremental, thus, more effective. We also expect that this generalized local propagation module enables us to develop an effective constraint hierarchy system with inter hierarchy comparison [20]. The complete PROLOG source code of all above mentioned modules as well as the code for modules implementing other predicate comparators is available on line at URL: http: kti.ms.mff.cuni.cz bartak prolog.html. ....

Wilson, M., Borning, A., Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison, Tech. Report 89-05-04, Department of Computer Science and Engineering, University of Washington, July 1989

....alternatives to solve a goal are usually specified as different rules for the same literal. This fact raises some problems, since different choices of rules in the logic program may produce solutions arriving from different constraint hierarchies, sometimes producing non intuitive solutions. In [11] the HCLP scheme is extended with some non monotonic properties of comparators to cope with interhierarchy comparisons. This problem was dealt with in IHCS by extending it with disjunctive constraints of the form c = c 1 W c 2 W Delta Delta Delta W c n , where c i is a normal ....

M. Wilson and A. Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonocity and Inter-Hierarchy Comparison. In Proceedings of the North American Conference 1989, 1989.

....the difference between the original and ours. 2. 1 The Original Theory of Constraint Hierarchies This section gives the original theory of constraint hierarchies proposed by Borning et al. They first presented a formulation of constraint hierarchies in [7] and later provided revised formulations [9, 11, 90, 91, 92, 93]. This section introduces their formulation based on [90] 1 2.1.1 Formulation Let X be the set of variables, D the domain of the variables, and C the set of constraints. A strength is an integer between 0 and l w , where l w is some positive integer. Intuitively, strength 0 indicates the ....

....two levels, and applies the least squares method to the weaker level [52, 59, 62, 82, 83] 7.4 Constraint Hierarchies This section presents previous work on constraint hierarchies from the viewpoints of theories and algorithms. 7.4. 1 Theories Borning et al. formulated constraint hierarchies [7, 9, 11, 90, 91, 92, 93], and studied their properties [9, 91] They also integrated constraint hierarchies with logic programming as hierarchical constraint logic programming (HCLP) and explored theoretical properties of HCLP [11, 90, 91, 92, 93] Jampel constructed a certain HCLP instance that separates the HCLP ....

[Article contains additional citation context not shown here]

Wilson, M. and A. Borning, "Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison," in Proceedings of the North American Conference on Logic Programming, 1989.

....to CP95. 1 Background 1. 1 Introduction The Hierarchical Constraint Logic Programming (HCLP) scheme of Borning, Wilson, and others [2, 11, 13] greatly extends the expressibility of the general CLP scheme [6] There is also related work by Satoh [10] A semantics has been defined for HCLP [11, 12] and some instances of it have been implemented [9, 11] However, the semantics is not as natural as one might hope, and the implementations are inherently less efficient than those of CLP. We believe that these two issues may be related, and suggest that splitting HCLP into two parts, one of ....

Molly Wilson and Alan Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison. In NACLP'89, 1989.

....those models where a given bird flies are preferred over those where it does not. Logic Programming Using the notion of a preferential theory, we were able to give a finitary characterization of the stable models of a normal logic program [7] Constraint Relaxation In a series of papers [3] [26], Borning and his students have introduced the notion of constraint hierarchies in logic programming. This work was done in the context of Constraint Logic Progamming, where a partial order (giving the order in which to relax the constraints if all of them cannot be satisfied) is placed on the ....

Wilson, M., and Borning, A. Extending hierarchical constraint logic programming: Nonmonotonicity and inter-hierarchy comparison. In NACLP (Cleveland, Ohio, 1989).

....of constraint hierarchies before presenting HCLP languages. We then present relational optimization. We compare the advantages and disadvantages of the two schemes before evaluating the performances of the relational optimization approach. 2 HCLP approach HCLP languages were presented in [1] [17] [18] as an approach to express preferences in CLP [8] These languages integrate constraint hierarchies and logic programming. 2.1 Constraint Hierarchies A labelled constraint is a constraint c labelled with a strength s and is written c s. The strengths range from 0 to n where n is the number ....

....it satisfies more constraints in its respective hierarchy than the first answer. These sort of problems have led to an extension of the notion of comparators to allow comparisons for solutions arising from different constraint hierarchies. These extended comparators were first presented in [17], and are called inter hierarchy comparators. 2.3 Inter hierarchy comparators In this extended model we consider not just one but several hierarchies, and the definitions are simply extended to cover this more general case. The tree of CSLD derivations associated for a given goal returns the set ....

[Article contains additional citation context not shown here]

M. Wilson and A. Borning. Extending hierarchical constraint logic programming: Nonmonotonicity and inter-hierarchy comparison. In E. Lusk and R. Overbeek, editors, NACLP89, pages 3--19. MITP, oct 1989.

....networks in graphical user interfaces. Basically, it is efficient because it uniquely solves a single constraint in each step. In addition, when a variable value is repeatedly updated by an operation such 3 Wilson and Borning refer to the property, in a less familiar word, as disorderly [12]. Instead, they use nonmonotonicity for another concept in hierarchical constraint logic programming. as dragging in interactive interfaces, it can easily re evaluate only the necessary constraints. However, local propagation has been restricted to multi way equality constraints which can be ....

....that can be simultaneously solved or properly relaxed [6] 2 Related Work This section briefly overviews previous researches on nonmonotonic constraint systems from the viewpoint of local propagation. Borning et al. the originators of constraint hierarchies [1] studied properties of hierarchies [2, 12], and also developed local propagation algorithms called DeltaBlue [4] and SkyBlue [9] However, their research on theoretical properties did not cover local propagation on constraint hierarchies, but rather mainly focused on hierarchical constraint logic programming (HCLP) 11, 12, 13] Jampel ....

[Article contains additional citation context not shown here]

Wilson, M. and A. Borning, "Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison," in Proc. North American Conference on Logic Programming, 1989.

....the context of the INTAS project 93 1702 Efficient Symbolic Computing. 1 Introduction The Hierarchical Constraint Logic Programming (HCLP) scheme of Borning, Wilson, and others [2, 14, 16] greatly extends the expressibility of the general CLP scheme [7] A semantics has been defined for HCLP [14, 15] and some instances of it have been implemented [12, 14] The Partial Constraint Satisfaction (PCSP) scheme of Freuder and Wallace [3, 5] is an interesting extension of CSP, which allows the relaxation and optimisation of problems. Extensive empirical studies have been made of some of its ....

Molly Wilson and Alan Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison. In NACLP'89 Cleveland, Ohio, 1989.

....the context of the INTAS project 93 1702 Efficient Symbolic Computing. 1 Introduction The Hierarchical Constraint Logic Programming (HCLP) scheme of Borning, Wilson, and others [3, 10, 12] greatly extends the expressibility of the general CLP scheme [7] A semantics has been defined for HCLP [10, 11] and some instances of it have been implemented [8, 10] The Partial Constraint Satisfaction (PCSP) scheme of Freuder and Wallace [4, 6] is an interesting extension of CSP, which allows the relaxation and optimisation of problems. Extensive empirical studies have been made of some of its instances ....

Molly Wilson and Alan Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison. In NACLP'89 Cleveland, Ohio, 1989.

....at any higher level. The only exception to this may be in the case of regional comparators which consider more than one level of the hierarchy at once. 3 Monotonicity and Fairness It is recognised that, unlike most standard constraint schemes, HCLP is non monotonic (note the subtitle of [8]) Thus the standard compositional properties for sets of solutions based on intersection do not carry over into the hierarchical view. We have analysed what aspect of HCLP causes the non monotonicity; it appears to us that HCLP suffers from discontinuities when, on backtracking say, the solution ....

....one of which is 11:00 a.m. But it seems more natural to accept the solution to the second hierarchy, which schedules the meeting at 6:00 p.m. as this would satisfy both the people who strongly want to attend the meeting. So some kind of inter hierarchy comparison is needed, as is discussed in [7, 8]. In FH2, one could have a meta preference, namely that if one hierarchy is completely dealt with but another stops prematurely due to a same level clash, the solutions to the former are to be preferred, as they have arisen from a more complete analysis of (one solution of) the problem. Should we ....

Molly Wilson and Alan Borning, "Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison," In NACLP'89: Proceedings North American Conference on Logic Programming, pp. 3--19, 1989.

....arising from the first hierarchy and those arising from the second with respect to how well a solution satisfies its own hierarchy. Clearly we wouldn t want to compare say 1:00 p.m. and 6:00 p.m. using just one of the hierarchies. 1:00 p.m. isn t even a solution to the second hierarchy ) In [81] the original constraint hierarchy theory was extended to allow for just such inter hierarchy comparisons. In what follows, the definitions from Section 2 are similarly extended. A solution to a set of constraint hierarchies 1 will consist of a set of valuations for all the free variables in 1. In ....

....S 01 , we define the set S1 as before, only now we are comparing across different hierarchies. Thus we eliminate potential valuations that are worse than some other from any hierarchy in 1. Extending the definition in this way gives rise to some nonmonotonic properties. These are discussed in [81]. We should point out that inter hierarchy comparison only makes sense with respect to the global comparators where the errors at each level in the hierarchy are conglomerated, and it is therefore reasonable to compare those errors arising from completely different sets of constraints. For the ....

[Article contains additional citation context not shown here]

Molly Wilson and Alan Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison. In Proceedings of the North American Conference on Logic Programming, pages 3--19, Cleveland, October 1989.

.... [4, 16] A number of instances of this scheme have now been implemented, including CLP(R) 12] Prolog III [5] and CHIP [6, 26] Two generalizations of the CLP scheme are CLP [13] which generalizes CLP by allowing predicates to be defined dynamically as first class objects, and HCLP [2, 28], which generalizes CLP by including constraint hierarchies rather than just required constraints. Finally, in the cc languages [23, 24] the conventional store of a Von Neumann computer is replaced by one that holds constraints. Concurrently executing agents communicate by asking and telling ....

Molly Wilson and Alan Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison. In Proceedings of the North American Conference on Logic Programming, Cleveland, October 1989.

No context found.

Wilson, M., Borning, A., Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison, Tech. Report 89-05-04, Department of Computer Science and Engineering, University of Washington, July 1989

No context found.

Wilson, M., Borning, A., Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison, Tech. Report 89-05-04, Department of Computer Science and Engineering, University of Washington, July 1989

No context found.

Molly Wilson and Alan Borning. Extending Hierarchical Constraint Logic Programming: Nonmonotonicity and Inter-Hierarchy Comparison. In NACLP'89, 1989.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC