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排序方式: 共有146条查询结果,搜索用时 15 毫秒
1.
The discrimination problem for two normal populations with the same covariance matrix when additional information on the population is available is considered. A study of the robustness properties against training sample contamination of classification rules that incorporate this additional information is performed. These rules have received recently attention where their total misclassification probability (TMP) is proved to be lower than Fisher's linear discriminant rule. The results of a simulation study on the TMP which compares the behaviour of the new rules against Fisher's rule and some of its robustified versions under different types of contamination are presented. These results show that the rules that incorporate the additional information not only have lower TMP, but they also prevent against some types of contamination. In order to achieve prevention from all types of contamination a robustifed version of these rules is recommended. 相似文献
2.
Xiuming Huang 《Machine Translation》1988,3(2):101-120
This paper concerns the resolution of lexical ambiguity in a machine translation environment. We describe the integration of principles of selection restrictions. Preference Semantics, and intelligent relaxation of constraints in handling lexical ambiguity. The approach differs from many previous MT systems in that it is more powerful than brute force systems, while more realistic than systems that assume a large degree of coded encyclopedia information for full understanding. 相似文献
3.
为提高大型通信网络中搜索满足多约束条件路由的速度,提出一种双向搜索路由的计算方法.首先从源和目的节点同时出发,计算到达各中间节点的可达路径.然后在各可达路径中进行路径的筛选.可达路径是采用邻接矩阵变换方式获得的,筛选路径是根据非线性开销函数,采用启发方式择优选取.当两方向搜索的节点数累计达到n-2后,对接合并两方向到达中间节点的路径,从中再选择最佳路径作为路由输出.通过算例详细介绍了可达路径计算及启发式选优方法.阐述了算法的正确性及特点,分析了最大时间杂性.通过仿真实验评估,不仅更进一步验证了新算法的正确性,而且表明新算法在搜索路由速度上要优于其他算法. 相似文献
4.
We describe the first shared task for figurative language resolution, which was organised within SemEval-2007 and focused
on metonymy. The paper motivates the linguistic principles of data sampling and annotation and shows the task’s feasibility
via human agreement. The five participating systems mainly used supervised approaches exploiting a variety of features, of
which grammatical relations proved to be the most useful. We compare the systems’ performance to automatic baselines as well
as to a manually simulated approach based on selectional restriction violations, showing some limitations of this more traditional
approach to metonymy recognition. The main problem supervised systems encountered is data sparseness, since metonymies in
general tend to occur more rarely than literal uses. Also, within metonymies, the reading distribution is skewed towards a
few frequent metonymy types. Future task developments should focus on addressing this issue.
相似文献
Malvina NissimEmail: |
5.
Maruti Mudunuru 《先进材料力学与结构力学》2017,24(7):556-590
This article concerns mesh restrictions that are needed to satisfy several important mathematical properties—maximum principles, comparison principles, and the nonnegative constraint—for a general linear second-order elliptic partial differential equation. We critically review some recent developments in the field of discrete maximum principles, derive new results, and discuss some possible future research directions in this area. In particular, we derive restrictions for a three-node triangular (T3) element and a four-node quadrilateral (Q4) element to satisfy comparison principles, maximum principles, and the nonnegative constraint under the standard single-field Galerkin formulation. Analysis is restricted to uniformly elliptic linear differential operators in divergence form with Dirichlet boundary conditions specified on the entire boundary of the domain. Various versions of maximum principles and comparison principles are discussed in both continuous and discrete settings. In the literature, it is well-known that an acute-angled triangle is sufficient to satisfy the discrete weak maximum principle for pure isotropic diffusion. Herein, we show that this condition can be either too restrictive or not sufficient to satisfy various discrete principles when one considers anisotropic diffusivity, advection velocity field, or linear reaction coefficient. Subsequently, we derive appropriate restrictions on the mesh for simplicial (e.g., T3 element) and nonsimplicial (e.g., Q4 element) elements. Based on these conditions, an iterative algorithm is developed to construct simplicial meshes that preserve discrete maximum principles using existing open source mesh generators. Various numerical examples based on different types of triangulations are presented to show the pros and cons of placing restrictions on a computational mesh. We also quantify local and global mass conservation errors using representative numerical examples and illustrate the performance of metric. 相似文献
6.
The Mixed Capacity Arc Routing Problem under Time Restrictions with Intermediate Facilities (MCARPTIF) is an extension of the Arc Routing Problem under Capacity and Length Restrictions with Intermediate Facilities (CLARPIF) with application in municipal waste collection. This paper evaluates four constructive heuristics capable of computing feasible solutions for the MCARPTIF with a primary objective to either minimise total cost or to minimise the fleet size. The heuristics were adapted from Path-Scanning and Improved-Merge for the Mixed Capacitated Arc Routing Problem, and compared against two Route-First-Cluster-Second heuristics for the MCARPTIF. The objective was to identify the best performing heuristic for application purposes. In practice, the CARP is often solved for real-time or near real-time decision support. Computational time required by the heuristics was thus also evaluated. Identifying the best heuristic proved difficult due to a lack of realistic MCARPTIF benchmark sets, with the two CLARPIF sets predominantly solved in the literature not resembling actual waste collection instances. Route-First-Cluster-Second heuristics, linked with a new vehicle reduction heuristic performed the worst on the two CLARPIF sets, yet performed the best on new waste collection sets taken from the literature and introduced in this paper. Improved-Merge performed the best on two existing CLARPIF sets and on a realistic set with Intermediate-Facilities incident with the vehicle depot, but struggled on all other sets and in minimising fleet size. Path-Scanning was the most robust heuristic, performing reasonably well on all benchmark sets and both objectives. Results further show that due to the high computational time of one of the Route-First-Cluster-Second heuristics, which was only exposed on realistically sized sets, the slightly worse version is the best alternative when real-time support is required for waste collection applications. 相似文献
7.
8.
Guillem Godoy Hugo Hernández 《Applicable Algebra in Engineering, Communication and Computing》2009,20(2):187-205
Reachability, joinability and confluence properties are known to be undecidable for flat term rewrite systems (TRS). We give
shorter and conceptually simpler proofs of these results. We also prove undecidability of weak normalization and unique normalization
properties for flat TRS.
The first author was supported by Spanish Ministry of Education and Science by the FORMALISM project (TIN2007-66523) and by
the LOGICTOOLS-2 project (TIN2007-68093-C02-01). The second author was supported by Spanish Ministry of Education and Science
by the FORMALISM project (TIN2007-66523). 相似文献
9.
Timing and amount of exposure to a 2nd language in the acquisition of phonotactic restrictions was examined in 4 experiments. In Experiments 1 and 2, 10-month-old monolingual and bilingual Catalan-Spanish infants were presented with nonwords that were phonotactically legal or illegal in Catalan and phonotactically illegal in Spanish. Differences between the 4 groups of infants were obtained as a function of language dominance. In Experiments 3 and 4, adult Spanish-Catalan bilinguals were compared with the same materials. Catalan-dominant bilinguals were more accurate than Spanish-dominant bilinguals in their perception of legal sequences; however, they were not more accurate with illegal sequences. The findings suggest a complex correlation between the pattern of preference and the amount and timing of exposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.