Using genetic algorithms to evolve a population of topical queries

Systems for searching the Web based on thematic contexts can be built on top of a conventional search engine and benefit from the huge amount of content as well as from the functionality available through the search engine interface. The quality of the material collected by such systems is highly dependant on the vocabulary used to generate the search queries. In this scenario, selecting good query terms can be seen as an optimization problem where the objective function to be optimized is based on the effectiveness of a query to retrieve relevant material. Some characteristics of this optimization problem are: (1) the high-dimensionality of the search space, where candidate solutions are queries and each term corresponds to a different dimension, (2) the existence of acceptable suboptimal solutions, (3) the possibility of finding multiple solutions, and in many cases (4) the quest for novelty. This article describes optimization techniques based on Genetic Algorithms to evolve “good query terms” in the context of a given topic. The proposed techniques place emphasis on searching for novel material that is related to the search context. We discuss the use of a mutation pool to allow the generation of queries with new terms, study the effect of different mutation rates on the exploration of query-space, and discuss the use of a especially developed fitness function that favors the construction of queries containing novel but related terms.     

构建环境适应型英语学习评价模型

评价作为一种价值判断过程,势必涉及环境因素,包括社会环境、学校环境和学习者环境。环境在评价中的作用要求英语学习评价必须采用环境适应型评价模型,根据价值主体的需求设置评价标准,设计评价过程;根据环境的具体需求调整评价结构、选择评价方式;遵循学习规律,适应学习者的多元需求,采用真实性评价方式。同时,为了保证评价的效度,必须对评价的结构、过程、结果和反馈进行元评价。     

Effectiveness during ball screens in elite basketball games

Ball screens are one of the most frequently used tactical behaviour in elite basketball games. The aim of the present study was to identify their predictors of success related to time, space, players, and tasks performed. The sample was composed of 818 ball screens corresponding to 20 close games (mean differences in score of 3.1 ± 0.8 points) randomly selected from the playoff games of the Spanish Basketball League (2008–2011). Classification tree analysis (CHAID) was used to analyse which variable or combination of variables, better predicts effectiveness during ball screens. The main results allowed identifying interactions with dribbler actions after the screen and the orientation of the screen on the ball. The results showed no interaction with game quarter and quarter minute temporal-related variables in both analyses. The present findings allow improving coaches’ strategic plans that involve selecting the most appropriate offensive approach when performing ball screens.     

语篇语法与精读课一体化模式探讨

语篇语法脱离了句法层面的分析,从超句的层次把握句子和段落之间的关系,解读语流中话语或篇章的含义。文章基于语法三大元功能之语篇功能的理论基础,探讨了主位结构、信息结构、衔接系统在英语专业精读课上的应用,并联系语境分析把握语篇外部环境对语篇的影响,改变传统语法课的教学模式,使语法课与精读课一体化,更有利于语法教学的持续、有效开展。     

Logical inferences in discourse analysis

Cohesion and coherence are two important characteristics of discourses. Halliday and Hasan have pointed out that cohesion is the basis of coherence and coherence is the premise of forming discourse. Th...     

A multi-criteria approach for the group assessment of an academic course: A case study

The present paper aims at proposing a structured methodology to evaluate the results of an academic training course addressed to postgraduate students. The evaluation process intends to identify the efficacy of an education course by means of a comparison between the general objectives and the results expected by the students. Since the evaluated aspects by the students, detected by means of questionnaires, are both quantitative and qualitative, the proposed methodology is based on the analytic hierarchy process (AHP). In order to facilitate the evaluation process, answers have been modelled by means of linguistic variables. In particular, different evaluation scales have been used and each one is characterized by different levels associated to different fuzzy numbers.     

学生个体差异:研究方法与基本结构

对课堂教学中学生个体差异的研究主要有两种方法:一是类型化研究,二是差异变量分析。其中差异变量分析是全面动态把握学生个体差异的较好方法。从影响学生学习的主体因素角度来分析,课堂教学中学生的个体差异主要包括基础性差异、动力性差异、操作性差异和方向性差异等四个方面,它们共同构成了课堂教学中学生个体差异变量的分析框架,为我们全面检视课堂教学中学生个体差异的真实状况提供了有效的检视工具。     

A review of ontology based query expansion

This paper examines the meaning of context in relation to ontology based query expansion and contains a review of query expansion approaches. The various query expansion approaches include relevance feedback, corpus dependent knowledge models and corpus independent knowledge models. Case studies detailing query expansion using domain-specific and domain-independent ontologies are also included. The penultimate section attempts to synthesise the information obtained from the review and provide success factors in using an ontology for query expansion. Finally the area of further research in applying context from an ontology to query expansion within a newswire domain is described.     

Very long-term retention of the control of variables strategy following a brief intervention

Middle school students (n = 354) were tested for their understanding of the control of variables strategy (CVS) 2.5 years after participating in a study comparing three different interventions for teaching CVS. The key finding was that the pattern of effects observed in the 4^th grade continued to be observed in the 6^th grade. This was because (a) students who had mastered CVS in the 4^th grade were likely to continue to perform at mastery levels in the 6^th grade whereas (b) the learning of students who had not mastered CVS in 4^th grade was independent of the teaching intervention they had received in the 4^th-grade study. These findings demonstrate that a brief intervention of direct instruction in CVS can produce long-lasting learning of the principle of controlling variables.     

基于句法依赖关系模板的术语相似度计算方法

针对现有基于语境特征的术语相似度算法在语境模板生成和匹配过程中存在的不足,提出基于术语的句法依赖关系自动构造术语语境模板,进而通过语境模板匹配计算术语相似度的方法。该方法既能减少语境模板的生成和匹配困难,又将术语语境特征较好地保留在模板中。针对新方法提出具体的实现步骤,并选取基因工程领域实验数据对新方法和现有典型方法进行对比评测。实验证明,新方法在计算效果方面具有明显提升。