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1.
We present a new axiomatization of logic for dependencies in data with grades, which includes ordinal data and data over domains with similarity relations, and an efficient reasoning method that is based on the axiomatization. The logic has its ordinary-style completeness characterizing the ordinary, bivalent entailment as well as the graded-style completeness characterizing the general, possibly intermediate degrees of entailment. A core of the method is a new inference rule, called the rule of simplification, from which we derive convenient equivalences that allow us to simplify sets of dependencies while retaining semantic closure. The method makes it possible to compute a closure of a given collection of attributes with respect to a collection of dependencies, decide whether a given dependency is entailed by a given collection of dependencies, and more generally, compute the degree to which the dependency is entailed by a collection of dependencies. We also present an experimental evaluation of the presented method.  相似文献   

2.
We propose a collection of hybrid methods combining Newton’s method with frozen derivatives and a family of high-order iterative schemes. We present semilocal convergence results for this collection on a Banach space setting. Using a more precise majorizing sequence and under the same or weaker convergence conditions than the ones in earlier studies, we expand the applicability of these iterative procedures.  相似文献   

3.
In this paper a method to construct Kripke models for subtheories of constructive set theory is introduced that uses constructions from classical model theory such as constructible sets and generic extensions. Under the main construction all axioms except the collection axioms can be shown to hold in the constructed Kripke model. It is shown that by carefully choosing the classical models various instances of the collection axioms, such as exponentiation, can be forced to hold as well. The paper does not contain any deep results. It consists of first observations on the subject, and is meant to introduce some notions that could serve as a foundation for further research.  相似文献   

4.
Phylogenetic networks are a generalization of evolutionary or phylogenetic trees that allow the representation of conflicting signals or alternative evolutionary histories in a single diagram. Recently the Quartet-Net or “QNet” method was introduced, a method for computing a special kind of phylogenetic network called a split network from a collection of weighted quartet trees (i.e. phylogenetic trees with 4 leaves). This can be viewed as a quartet analogue of the distance-based Neighbor-Net (NNet) method for constructing outer-labeled planar split networks. In this paper, we prove that QNet is a consistent method, that is, we prove that if QNet is applied to a collection of weighted quartets arising from a circular split weight function, then it will return precisely this function. This key property of QNet not only ensures that it is guaranteed to produce a tree if the input corresponds to a tree, and an outer-labeled planar split network if the input corresponds to such a network, but also provides the main guiding principle for the design of the method.  相似文献   

5.
This paper considers a real world waste collection problem in which glass, metal, plastics, or paper is brought to certain waste collection points by the citizens of a certain region. The collection of this waste from the collection points is therefore a node routing problem. The waste is delivered to special sites, so called intermediate facilities (IF), that are typically not identical with the vehicle depot. Since most waste collection points need not be visited every day, a planning period of several days has to be considered. In this context three related planning problems are considered. First, the periodic vehicle routing problem with intermediate facilities (PVRP-IF) is considered and an exact problem formulation is proposed. A set of benchmark instances is developed and an efficient hybrid solution method based on variable neighborhood search and dynamic programming is presented. Second, in a real world application the PVRP-IF is modified by permitting the return of partly loaded vehicles to the depots and by considering capacity limits at the IF. An average improvement of 25% in the routing cost is obtained compared to the current solution. Finally, a different but related problem, the so called multi-depot vehicle routing problem with inter-depot routes (MDVRPI) is considered. In this problem class just a single day is considered and the depots can act as an intermediate facility only at the end of a tour. For this problem several instances and benchmark solutions are available. It is shown that the algorithm outperforms all previously published metaheuristics for this problem class and finds the best solutions for all available benchmark instances.  相似文献   

6.
The focus of this article is on conditional stability estimates for ill-posed inverse problems in partial differential equations. Conditional stability estimates have been obtained in related literature by a couple different methods. In this article, we propose a method called interpolation method, which is based on interpolation in variable Hilbert scales. We provide the theoretical background of this method and show that optimal conditional stability estimates are obtained. The capabilities of our method are illustrated by a comprehensive collection of different inverse and ill-posed PDE problems containing elliptic and parabolic problems, one source problem and the problem of analytic continuation.  相似文献   

7.
In this paper, we study a threshold level inventory rationing policy that is of interest to e-tailers, operating in a business to consumer (B2C) environment and selling non-perishable, made-to-stock items such as books, CDs, consumer electronics, and body and bath products. A Monte Carlo simulation model is developed to examine this policy when the demand process is stochastic, lead-time is stochastic, and the e-tailer uses ‘drop-shipping’ as an order fulfillment option. The methodology presented, which includes computer simulation and a full factorial experimental design, permits understanding of the complexity of the decision-making environment and implications of different sources of uncertainty (e.g. demand variability and lead-time variability) on a profit-maximizing threshold level of inventory, a stock level below which low margin orders are drop-shipped directly from the e-tailer’s supplier rather than fulfilled from internal stock.  相似文献   

8.
顾桂定  王德人 《计算数学》1999,21(4):417-428
1.引言实际问题中经常要遇到一族函数极小值问题的求解,即minfi(x),i=1,...,P;(1.1)其中人:R"、R具有公共的Hessian矩阵G(x)。7'fi(x),r是适中的数值.如在各种负载下的弹性体研究中,即要遇到问题(l.I)的求解,其中人(C)一人C)+qC十C;(=1,...,....对于不同的比则人(X)具有不同的极小点和不同的梯度D人(X),但具有相同的Hessian矩阵G(X).1994年,O'Leary等【']把拟一Newton算法推广至成组形式(multiPleversio...,…  相似文献   

9.
This paper describes an approach developed to minimize the cost of refuse collection operations in a city of 150,000 population. The method is general and applicable to a city of any size.A model is derived for collection which is a function of varied housing layouts, collection times, team sizes and the distance of the collection rounds from the disposal point. Then a computational method is developed which allocates collection operatives to vehicles and designs rounds which together minimize the total collection cost.The advantages of the method are:(a) It reduces collection costs. The “one-off” cost of applying the method to 10 per cent of the local authorities in the U.K. would be [pound]150,000 and yield a reduction in costs of [pound]500,000 p.a.(b) It enables management to replan rounds quickly as circumstances change.(c) Other applications, which are being investigated, are also discussed.  相似文献   

10.
广义块Broyden方法与超定方程组求解   总被引:1,自引:1,他引:0  
顾桂定 《计算数学》1997,19(4):375-384
1.引言[1]提出用块Broyden方法求解成组的线性与非线性方程组,同时证明了:若有p组n阶线性方程组则块Brorden方法具有至多2n/p步的有限终止性.这种块形式算法,对于大型成组问题的计算,在计算量和存储量方面,都会有相当的改善,并且有利于并行计算.本文推广上述结果,建立一种广义块nroxaen方法,并将它应用于成组的超定方程组的求解.我们证明了对于给出的p组。x叫x三叫的线性超定方程组其中AeRm””,x;e*”,kEBm,广义块Broxden方法同样具有至多z。/r步的有限终止性,这表明超定方程组的纽数越多(P5…,方法所需的选代…  相似文献   

11.
ROSAT is a satellite borne X-ray observatory. Mission planning consists of scheduling up to half a year in advance a preselected large collection of targets. It is shown that a relaxation of the ROSAT scheduling problem can be modeled as a generalized assignment problem and that the solutions obtained with this method lead to good solutions of the non-relaxed problem. Other heuristics as well as upper bounds on the quality of solutions are discussed.  相似文献   

12.
A method has been described for classifying a collection of items characterized by qualitative attributes. The method uses mainly two concepts, typicality and similarity. The first of these has been derived by applying information-theoretical tools to the data. Typicality is a relation of one item to the whole collection. Similarity is a one-to-one relation between two items and depends on the number of common properties shared by them.The method has been programmed for the IBM 1620 computer.  相似文献   

13.
In family studies with multiple continuous phenotypes, heritability can be conveniently evaluated through the so-called principal-component of heredity (PCH, for short; Ott and Rabinowitz in Hum Hered 49:106–111, 1999). Estimation of the PCH, however, is notoriously difficult when entertaining a large collection of phenotypes which naturally arises in dealing with modern genomic data such as those from expression QTL studies. In this paper, we propose a regularized PCH method to specifically address such challenges. We show through both theoretical studies and data examples that the proposed method can accurately assess the heritability of a large collection of phenotypes.  相似文献   

14.
In this work, we present a new hybrid conjugate gradient method based on the approach of the convex hybridization of the conjugate gradient update parameters of DY and HS+, adapting a quasi-Newton philosophy. The computation of the hybrization parameter is obtained by minimizing the distance between the hybrid conjugate gradient direction and the self-scaling memoryless BFGS direction. Furthermore, a significant property of our proposed method is that it ensures sufficient descent independent of the accuracy of the line search. The global convergence of the proposed method is established provided that the line search satisfies the Wolfe conditions. Our numerical experiments on a set of unconstrained optimization test problems from the CUTEr collection indicate that our proposed method is preferable and in general superior to classic conjugate gradient methods in terms of efficiency and robustness.  相似文献   

15.
回归分析在测定最佳图书复本量中的应用   总被引:2,自引:0,他引:2  
本文从调查图书馆图书复本量分布及其读者借阅图书的分布情况出发,应用回归分析方法得出图书复本量与实际拒借率为双曲线回归关系,并以求解该双曲线的最大曲率点坐标,测得最佳图书复本量的值和对应的理想拒借率。  相似文献   

16.
Summary. We consider a quadratic programming-based method for nonlinear complementarity problems which allows inexact solutions of the quadratic subproblems. The main features of this method are that all iterates stay in the feasible set and that the method has some strong global and local convergence properties. Numerical results for all complementarity problems from the MCPLIB test problem collection are also reported. Received February 24, 1997 / Revised version received September 5, 1997  相似文献   

17.
We present an approach to studying the community structures of networks by using linear programming (LP). Starting with a network in terms of (a) a collection of nodes and (b) a collection of edges connecting some of these nodes, we use a new LP-based method for simultaneously (i) finding, at minimal cost, a second edge set by deleting existing and inserting additional edges so that the network becomes a disjoint union of cliques and (ii) appropriately calibrating the costs for doing so. We provide examples that suggest that, in practice, this approach provides a surprisingly good strategy for detecting community structures in given networks.   相似文献   

18.
19.
An active set subspace Barzilai-Borwein gradient algorithm for large-scale bound constrained optimization is proposed. The active sets are estimated by an identification technique. The search direction consists of two parts: some of the components are simply defined; the other components are determined by the Barzilai-Borwein gradient method. In this work, a nonmonotone line search strategy that guarantees global convergence is used. Preliminary numerical results show that the proposed method is promising, and competitive with the well-known method SPG on a subset of bound constrained problems from CUTEr collection. This work was supported by the 973 project granted 2004CB719402 and the NSF project of China granted 10471036.  相似文献   

20.
This paper addresses a general sampling method to estimate the Banzhaf–Owen value for general cooperative TU-games. It is based on systematic sampling techniques on the set of those coalitions that are compatible with the structure of a priori unions. This procedure is theoretically analysed by establishing a collection of statistical properties. Finally, we evaluate this tool on approximating the power of the members of the Executive Board of Governors of the International Monetary Fund (IMF) in 2002 and 2016.  相似文献   

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