This paper explores an approach to design for verification in systems built atop a middleware framework which separates synchronization concerns from the "core-functional logic" of a program. The framework i...
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This paper explores an approach to design for verification in systems built atop a middleware framework which separates synchronization concerns from the "core-functional logic" of a program. The framework is based on a language-independent compositional model of synchronization contracts, called Szumo, which integrates well with popular OO design artifacts and provides strong guarantees of non-interference for a class of strictly exclusive systems. An approach for extracting models from Szumo design artifacts and analyzing the generated models to detect deadlocks is described. A key decision was to use constraint Handling Rules to express the semantics of synchronization contracts, which allowed a transparent model of the implementation logic.
This paper describes and evaluates approaches to model and solve technical product configuration problems using different artificial intelligence methodologies. By means of a typical example, the benefits and limitati...
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This paper describes and evaluates approaches to model and solve technical product configuration problems using different artificial intelligence methodologies. By means of a typical example, the benefits and limitations of different artificial intelligence methods are discussed and a flexible software architecture for integrating different solvers in a product configurator is proposed.
We define value constraints, a method for incorporating constraint propagation into logicprogramming. It is a subscheme of the CLP scheme and is applicable wherever one has an efficient method for representing sets o...
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We define value constraints, a method for incorporating constraint propagation into logicprogramming. It is a subscheme of the CLP scheme and is applicable wherever one has an efficient method for representing sets of possible values. As examples we present: small finite sets, sets of ground instances of a term, and intervals of reals with floating-point numbers as bounds. Value constraints are defined by distinguishing two storage management strategies in the CLP scheme. In value constraints the infer step of the CLP scheme is implemented by Waltz filtering. We give a semantics for value constraints in terms of set algebra that gives algebraic characterizations of local and global consistency. The existing extremal fixpoint characterization of chaotic iteration is shown to be applicable to prove convergence of Waltz filtering.
Resource-constrained scheduling problems appear at different levels of decisions in logistics, manufacturing, computer networks, software engineering etc. They are usually characterized by many types of constraints an...
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ISBN:
(纸本)9783319465838;9783319465821
Resource-constrained scheduling problems appear at different levels of decisions in logistics, manufacturing, computer networks, software engineering etc. They are usually characterized by many types of constraints and decision variables which often make them difficult to solve (NP-complete). In addition, these problems are often characterized by the uncertainty of resources, allocations and time. Opportunity to ask questions and get answers about the feasibility/optimality of a schedule in uncertain conditions (e.g. about available resources) is extremely important for decision-makers. This paper presents a hybrid approach to modeling and solving robust constrained scheduling problems where two environments (mathematical programming and constraint logic programming) were integrated. This integration, hybridization as well as a transformation of the problem helped reduce the combinatorial problem substantially. In order to compare the effectiveness of the proposed approach to the mathematical programming approach, illustrative example was implemented in both environments for the same data instances.
Policy specification languages such as XACML often provide mechanisms to resolve dynamic conflicts that occur when trying to determine if a request should be permitted or denied access by a policy. Examples include &q...
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ISBN:
(纸本)9781509009909
Policy specification languages such as XACML often provide mechanisms to resolve dynamic conflicts that occur when trying to determine if a request should be permitted or denied access by a policy. Examples include "deny-overrides" or "first-applicable." Such algorithms are primitive and potentially a risk for corporate computer security. While they can be useful for resolving dynamic conflicts, they are not justified for conflicts that can be easily detected statically. It is better to find those at compile time and remove them before run time. Many different approaches have been used for static conflict detection. However, most of them do not scale well because they rely on pair-wise comparison of the access control logic of policies and rules. We propose an extension of a Prolog-based expert system approach due to Eronen and Zitting. This approach uses constraint logic programming techniques (CLP), which are well-adapted to hierarchical XACML policy logic and avoid pair-wise comparisons altogether by taking advantage of Prolog's built-in powerful indexing system. We demonstrate that expert systems can indeed detect conflicts statically, even those that are generally believed to only be detectable at run time, by inferring the values of attributes that would cause a conflict. As a result, relying on the XACML policy combining algorithms can be avoided in most cases except in federated systems. Finally we provide performance measurements for two different architectures represented in Prolog and give some analysis.
Testing is a vital part of the software development process. Test Case Generation (TCG) is the process of automatically generating a collection of test-cases which are applied to a system under test. White-box TCG is ...
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Testing is a vital part of the software development process. Test Case Generation (TCG) is the process of automatically generating a collection of test-cases which are applied to a system under test. White-box TCG is usually performed by means of symbolic execution, i.e., instead of executing the program on normal values (e.g., numbers), the program is executed on symbolic values representing arbitrary values. When dealing with an object-oriented (OO) imperative language, symbolic execution becomes challenging as, among other things, it must be able to backtrack, complex heap-allocated data structures should be created during the TCG process and features like inheritance, virtual invocations and exceptions have to be taken into account. Due to its inherent symbolic execution mechanism, we pursue in this paper that constraint logic programming (CLP) has a promising application field in TCG. We will support our claim by developing a fully CLP-based framework to TCG of an OO imperative language, and by assessing it on a corresponding implementation on a set of challenging Java programs.
We present an integration of answer set programming and constraint processing as an interesting approach to constraint logic programming. Although our research is in a very early stage, we motivate constraint answer s...
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ISBN:
(纸本)9783939897170
We present an integration of answer set programming and constraint processing as an interesting approach to constraint logic programming. Although our research is in a very early stage, we motivate constraint answer set programming and report on related work, our research objectives, preliminary results we achieved, and future work.
Managing a patient with comorbid diseases according to multiple clinical practice guidelines (CPGs) may result in adverse interactions that need to be mitigated (identified and addressed) so a safe therapy can be devi...
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ISBN:
(纸本)9781614992899;9781614992882
Managing a patient with comorbid diseases according to multiple clinical practice guidelines (CPGs) may result in adverse interactions that need to be mitigated (identified and addressed) so a safe therapy can be devised. However, mitigation poses both clinical and methodological challenges. It requires extensive domain knowledge and calls for advanced CPG models and efficient algorithms to process them. We respond to the above challenges by describing our algorithm that mitigates interactions between pairs of CPGs. The algorithm creates logical models of analyzed CPGs and uses constraint logic programming (CLP) together with domain knowledge, codified as interaction and revision operators, to process them. logical CPG models are transformed into CLP-CPG models that are solved to find a safe therapy. We represent these CLP-CPG models using MiniZinc, a standard language for CLP models. As motivation and illustration of our mitigation algorithm we use a clinical case study describing a patient managed for hypertension and deep vein thrombosis according to two individual CPGs. We apply the algorithm to this scenario and present MiniZinc representations of the constructed CLP-CPG models.
Supply chain problems cover several aspects at different levels and areas. There are decision on production allocation, resource allocation, production and inventory quantities, distributor selection, choice of transp...
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ISBN:
(纸本)9783319393872;9783319393865
Supply chain problems cover several aspects at different levels and areas. There are decision on production allocation, resource allocation, production and inventory quantities, distributor selection, choice of transportation mode etc. There are many constraints in the supply chain problems. They concern the following areas ( production, distribution, transport, etc.) and types ( linear, non-linear, integer, logical, etc.). Therefore it is important effective modeling and solving constraints. We consider a multi-level and multi-agent approach to modeling and solving supply chain problems using constraint and mathematical programming environments. Its efficiency results from the multi-level presolving and multi-agent architecture. An illustrative example presents effectiveness of the proposed approach. The presented approach will be compared with classical mathematical programming on the same data sets.
The paper focuses on a selected class of decision problems related with the production flow planning in SMEs, particularly in new production orders. Verification of orders gives a possibility to evaluate whether resou...
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ISBN:
(纸本)9780780397583
The paper focuses on a selected class of decision problems related with the production flow planning in SMEs, particularly in new production orders. Verification of orders gives a possibility to evaluate whether resources capacity of a manufacturer is balanced with the orderer's requirements. The class of decision problems under analysis is included in the scope of organizational production preparation and can be naturally determined by available CLP (constraint logic programming) tools. The approach proposed in the paper is based on establishment of an interface which facilitates its task oriented use. The system has been presented on the basis of a sample order, execution in a manufacturer's company (Archimedes S.A.).
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