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排序方式: 共有6103条查询结果,搜索用时 31 毫秒
61.
作为作业调度里面一类典型问题,Job-shop问题的求解是属于NP完全的,至今大规模Job-shop问题的有效算法仍未找到.在析取有向图模型基础上,通过减聚类方法构建径向基函数神经网络实现可互换工序对选取,利用最小均方算法对网络权重进行训练,以此为基础提出一种具备学习功能智能算法.数值仿真结果表明,所提算法对于大规模Job-shop问题求解存在较好效果,达到预期目的. 相似文献
62.
Sven Hartmann 《Annals of Mathematics and Artificial Intelligence》2001,33(2-4):253-307
In database design, integrity constraints are used to express database semantics. They specify the way by that the elements of a database are associated to each other. The implication problem asks whether a given set of constraints entails further constraints. In this paper, we study the finite implication problem for cardinality constraints. Our main result is a complete characterization of closed sets of cardinality constraints. Similar results are obtained for constraint sets containing cardinality constraints, but also key and functional dependencies. Moreover, we construct Armstrong databases for these constraint sets, which are of special interest for example-based deduction in database design. 相似文献
63.
Robert Rodošek 《Constraints》2001,6(2-3):257-269
This paper presents an hybrid algorithm for deriving 3-D structures of cyclic polypeptides. The algorithm combines constraint-based techniques with the most widely used methods for non-cyclic polypeptides. The empirical results demonstrate that the proposed hybrid algorithm outperforms traditional methods especially with respect to running times. 相似文献
64.
Roland H. C. Yap 《Constraints》2001,6(2-3):157-172
Approximate matching techniques based on string alignment are important tools for investigating similarities between strings, such as those representing DNA and protein sequences. We propose a constraint based approach for parametric sequence alignment which allows for more general string alignment queries where the alignment cost can itself be parameterized as a query with some initial constraints. Thus, the costs need not be fixed in a parametric alignment query unlike the case in normal alignment. The basic dynamic programming string edit distance algorithm is generalized to a naive algorithm which uses inequalities to represent the alignment score. The naive algorithm is rather costly and the remainder of the paper develops an improvement which prunes alternatives where it can and approximates the alternatives otherwise. This reduces the number of inequalities significantly and strengthens the constraint representation with equalities. We present some preliminary results using parametric alignment on some general alignment queries. 相似文献
65.
现代产品设计的复杂性要求设计过程管理向高层转移,并能支持多领域并行设计,针对这种需求,文中提出基于问题解决模型的设计过程管理的概念与方法,将设计过程视为问题定义、规划与求解的过程,并利用过程描述语言捕获领域知识,通过设计过程文法,实现设计问题的求解与映射,该方法抓住设计过程的本质,可为设计者提供高层次跨领域的设计过程管理支持为设计周期的缩短提供了可能。 相似文献
66.
Hua Shu 《Journal of Intelligent Information Systems》2000,15(2):147-173
View update is the problem of translating update requests against a view into update requests against the base data. In this article, we present a novel approach to generating alternative translations of view updates in relational databases. Using conditional tables to represent relational views, we transform a view update problem into constraint satisfaction problems (CSPs). Solutions to the CSPs correspond to possible translations of the view update. Semantic information to resolve ambiguity can be incrementally added as constraints in the CSPs. The connection between view update and constraint satisfaction makes it possible to apply the rich results of the CSP research to analyze and solve the important problem of view management. 相似文献
67.
XIE Da-tong 《数字社区&智能家居》2008,(11)
从遗传算法的编码、遗传算子等方面剖析了遗传算法求解无约束函数优化问题的一般步骤,并以一个实例说明遗传算法能有效地解决函数优化问题。 相似文献
68.
This paper deals with four solvers for combinatorial problems: the commercial state-of-the-art solver ILOG oplstudio, and the research answer set programming (ASP) systems dlv, smodels and cmodels. The first goal of this research is to evaluate the relative performance of such systems when used in a purely declarative
way, using a reproducible and extensible experimental methodology. In particular, we consider a third-party problem library,
i.e., the CSPLib, and uniform rules for modelling and instance selection. The second goal is to analyze the marginal effects
of popular reformulation techniques on the various solving technologies. In particular, we consider structural symmetry breaking,
the adoption of global constraints, and the addition of auxiliary predicates. Finally, we evaluate, on a subset of the problems,
the impact of numbers and arithmetic constraints on the different solving technologies. Results show that there is not a single
solver winning on all problems, and that reformulation is almost always beneficial: symmetry-breaking may be a good choice,
but its complexity has to be carefully chosen, by taking into account also the particular solver used. Global constraints
often, but not always, help opl, and the addition of auxiliary predicates is usually worth, especially when dealing with ASP solvers. Moreover, interesting
synergies among the various modelling techniques exist. 相似文献
69.
Ting-Nung Shiau Chung-Hao Kang De-Shin Liu 《Structural and Multidisciplinary Optimization》2008,36(6):623-631
A new interval optimization algorithm is presented in this paper. In engineering, most optimization algorithms focus on exact
parameters and optimum objectives. However, exact parameters are not easy to be manufactured to because of manufacturing errors
and expensive manufacturing cost. To account for these problems, it is necessary to estimate interval design parameters and
allowable objective error. This is the first paper to propose a new interval optimization algorithm within the context of
Genetic Algorithms. This new algorithm, the Interval Genetic Algorithm (IGA), can neglect interval analysis and determines
the optimum interval parameters. Furthermore, it can also effectively maximize the design scope. The optimizing ability of
the IGA is tested through the interval optimization of a two-dimensional function. Then the IGA is applied to rotor-bearing
systems. The results show that the IGA is effective in deriving optimal interval design parameters within the allowable error
when minimizing shaft weight and/or transmitted force of rotor-bearing systems. 相似文献
70.
Architecture transformations are frequently performed during software design and maintenance.However this activity is not well supported at a sufficiently abstract level.In this paper,the authors characterize architecture transformations using using graph rewriting rules,where architectures are represented in graph notations,Architectures are usually required to satisfy certain constraints during evolution.Therefore a way is presented to construct the sufficient and necessary condition for a transformatio to preserve a constraint.The condition can be verified before the application of the transformation.Validated transformations are guaranteed not to violate corresponding constraints whenever applied. 相似文献