三类问题的破解与探索

在各地近几年的高考模拟试题中,频繁地出现这样三类问题:"向量"问题、"折线距离"问题及"面积"问题.每每遇到这类题学生往往不知所措,难以入手,所以非常容易出错.究其原因:一是问题本身新颖、知识点比较综合,对学生思维要求比较高;二是问题以能力立意为宗旨,问题中蕴含着丰富的数学思想与方法下面笔者就这三类问题     

重视问题提出 培养问题素养

<正>提出问题是创新的源泉,是教学活动的起点和归宿.《义务教育数学课程标准》(2011)中提出的课程总目标之一便是"增强发现和提出问题的能力、分析和解决问题的能力".爱因斯坦曾说过:"提出一个问题往往比解决一个问题更为重要."在课堂教学中,尽管越来越多的教师意识到提问的重要性,然而由于升学压力的因素,课堂教学还是局限在"教师提问,学生回答"的问答式交流活动中.课堂上教师忙于赶进度,部分教师仍然采用"满堂灌"的教学方法,学习主体对知识的发现和探究过程被忽略了,学生没有机会发现问题、提出问题,普     

“科克曼女生问题”的探讨

用初等数学三个步骤解析"科克曼女生问题";发现"科克曼女生问题"存在十三系列解;对"科克曼女生问题"的组解进行了初步计算.     

一个著名的数学问题——3x+1问题

有一个风靡世界有趣的"问题",人人都会演算,但要证明它却像对付坚硬的磐石,它似乎能轻而易举地挫去你智慧的锋芒。这就是尚未解决的数学难题之一——3x+1问题(也称角谷猜想、克拉茨问题、叙拉古问题)。"角谷猜想"又称"冰雹猜想"。它首先流传于美国,不久便传到欧洲,后来一位名叫角谷的日本人又把它带到亚洲,因而人们就顺势把它叫做     

基于运输问题“悖论”的最大运量问题研究

在文献[1]给出的运输问题"悖论"充要条件定理基础上,结合最小调整法,给出利用"悖论"存在,实现增加运量而使得总运费不增的经济调整方案,并给出具体实施步骤和途径,用实例加以验证,对带有"悖论"现象的运输问题最优方案的调整具有重要的实际意义。     

某些图论问题的进展

本文介绍了图论中某些问题的进展情况,其中问题1-50是Bondy和Murty著的"图论及其应用"一书附录Ⅳ中的问题,问题51-90是从其它方面收集来的新问题.     

新课程数学课堂教学设计中问题解决的有效性探究

1"问题解决"的含义关于"问题解决",主要有三种不同的理解:第一种理解把"问题解决"看成是一种教学手段,这是把"问题解决"从属于具体数学知识的教学,把"问题解决"当作一种背景,即通过问题来引入有关的教学内容,并通过问题解决来达到复习、巩固及检查的目的.第二种理解把"问题解决"看成是一种技     

精彩源于有价值的问题设计

"问题是数学的灵魂",优秀的数学教师都是设计问题、拓展问题和解决问题的高手.他们或化整为零,或顺学而问,或乘兴反问,在问题的"迂回辗转"和"深入挺进"中,发展学生的思维,提升学生的能力,锻造学生的品质.教师凭借"有价值的问题",使课堂有不一样的亮点和精彩的生成,师生或有突破,或有惊喜.教师应善于强化问题意识,创设螺旋式递进的问题情境,引领学生在探究延伸的问题中大展身手.     

浅谈定值问题的解题规律

《中学生数学》2010年第11期(月下)刊登了吴秀玲老师的文章"圆中定值问题若干例"(以下称"原文")."原文"中只给出了例题的解法,而未给出这些解法是如何想到的,而这恰恰是学生最想知道的问题!本文将结合"原文"中的例题,探讨解决这类问题的一般规律,供同学们学习时参考.     

容易混淆的"恒成立"问题与"存在成立"问题

不等式是中学数学的基础知识和重要部分,一直是各类考试、考查的热点与重点.不等式"恒成立"问题与"存在成立"问题,又是不等式中常见的题型.在各地的自主招生、高考、模拟考试中屡见不鲜.此二类问题对学生掌握基本数学思想与方法提出了较高的要求.学生对此二类问题往往感到容易混淆.     

工科数学改革诌议

本文试图从培养工科大学生的能力方面谈谈工科数学改革，强调工科数学教育应加强基础，扩大学生的知识面。     

Experiments on data reduction for optimal domination in networks

We present empirical results on computing optimal dominating sets in networks by means of data reduction through efficient preprocessing rules. Thus, we demonstrate the usefulness of so far only theoretically considered data reduction techniques for practically solving one of the most important network problems in combinatorial optimization.     

Tutorial on Surrogate Constraint Approaches for Optimization in Graphs

Surrogate constraint methods have been embedded in a variety of mathematical programming applications over the past thirty years, yet their potential uses and underlying principles remain incompletely understood by a large segment of the optimization community. In a number of significant domains of combinatorial optimization, researchers have produced solution strategies without recognizing that they can be derived as special instances of surrogate constraint methods. Once the connection to surrogate constraint ideas is exposed, additional ways to exploit this framework become visible, frequently offering opportunities for improvement.We provide a tutorial on surrogate constraint approaches for optimization in graphs, illustrating the key ideas by reference to independent set and graph coloring problems, including constructions for weighted independent sets which have applications to associated covering and weighted maximum clique problems. In these settings, the surrogate constraints can be generated relative to well-known packing and covering formulations that are convenient for exposing key notions. The surrogate constraint approaches yield widely used heuristics for identifying independent sets as simple special cases, and also afford previously unidentified heuristics that have greater power in these settings. Our tutorial also shows how the use of surrogate constraints can be placed within the context of vocabulary building strategies for independent set and coloring problems, providing a framework for applying surrogate constraints that can be used in other applications.At a higher level, we show how to make use of surrogate constraint information, together with specialized algorithms for solving associated sub-problems, to obtain stronger objective function bounds and improved choice rules for heuristic or exact methods. The theorems that support these developments yield further strategies for exploiting surrogate constraint relaxations, both in graph optimization and integer programming generally.     

半直线上随机环境中随机游动的极限性质

文对右半直线上在0点带有反射壁的随机环境中随机游动进行了研究,得到了在环境是平稳遍历条件下的常返准则及在环境是独立同分布条件下的一个强大数定律和中心极限定理.     

Lie symmetry analysis for classification on pattern in excitable media

The dynamics of wave front in two dimensional excitable media is described by the derivative Burgers’ equation. In this paper, we will carry out Lie symmetry analysis to the equation for constructing particular solutions associated with chemical patterns. The form of the variable coefficient in the reduced equation by using symmetries classifies the invariant solutions into three cases and the solutions include arc, circle, knee, spiral and double scroll patterns.     

Estimates for functions in Sobolev spaces defined on unbounded domains

Given a function u belonging to a suitable Beppo–Levi or Sobolev space and an unbounded domain Ω in , we prove several Sobolev-type bounds involving the values of u on an infinite discrete subset A of Ω. These results improve the previous ones obtained by Madych and Potter [W.R. Madych, E.H. Potter, An estimate for multivariate interpolation, J. Approx. Theory 43 (1985) 132–139] and Madych [W.R. Madych, An estimate for multivariate interpolation II, J. Approx. Theory 142 (2006) 116–128].     

对工科高等数学的研究性教学的一些认识

当前"研究性教学"是比较提倡的教学方式,它有利于培养学生的数学思想和数学素养.为了更好地进行"研究性教学",教师应研究数学史培养学生数学思想,应研究数学教学的认知规律培养学生"研究性学习"习惯,以及进行应用数学知识能力的研究,完美的逻辑体系与学生接受能力的研究,支持这种教学方式的考核方式的研究.     

Comments on algorithms for grid interfaces in simulating Euler flows

Some results concerning the algorithms for grid interfaces, which are crucial in simulating flows by zonal methods, are presented in this paper. It is indicated that the commonly used conservative interface scheme can ensure the discrete entropy condition, but it may be inconsistent and would bring a nonoverlapping solution on overlapping grids. A nonconservative interface matching obtained by interpolation can be monotonicity preserving, and it leads large conservation error when discontinuities are close to the interfaces. Methods for improvement of interface algorithms are also proposed.     

Models for use in Negotiations on Pay and Working Conditions

In this paper we develop three inter-related models, based on value added concepts, that can form the starting point for discussions on pay and working conditions at the plant level. The first model considers the factors that contribute to an increase in the added value (such as prices, sales volume and material productivity) and provides a relationship between relative changes in the values of these factors and the resulting relative change in the added value. In the second model the increase in the added value is assumed to be shared between the labourforce (through increased wages) and the management (who require funds to cover all other costs and make provision for profit); the relative change in wages is decomposed further to take into consideration the effect on the average employee's pay of possible changes in the labour productivity and/or the size of the workforce. The two models are then combined to produce the third model with a view to rewarding labour and management in proportion to each one's contribution towards improving the operational efficiency of the plant.All three models are simple and versatile enough to allow:

1. a)
   The use of alternative assumptions and functional relationships to reflect differing views of the negotiators;
    
2. b)
   sensitivity analyses to identify the most crucial assumptions and estimates that are likely to affect the results; and
    
3. c)
   further disaggregation to incorporate additional variables and a more detailed breakdown of the added value, wage rates or working hours, if this is thought to be desirable.
    

It is recommended that such models be developed, discussed and analysed by the negotiators themselves in an attempt to make them highlight the issues, arguments and important characteristics pertaining in each individual case. The models could then provide the basis of a common communication language leading to a better understanding of each other's position and, hopefully, to less conflict.