MATLAB在空间图形中的动态应用

学生空间思维的不足影响了学生对空间曲面的理解和重积分的学习。本文通过二个实例,重点讨论了用MATLAB动态生成空间图形的技巧。     

关于空间解析几何的学术形态和教育形态

空间解析几何知识需要形式化的表述,而学生掌握空间解析几何知识需要经过思考,需要追根求源．作为教师,必须善于将空间解析几何的学术形态转化为教育形态,激发学生的学习兴趣和主动性．结合自己在空间解析几何教学实践中的体会,给出了一些实例．     

利用几何画板制作动态的空间直角坐标系工具

如果有一个制作简单且使用方便的动态的空间直角坐标系工具,那么可以快捷制作一个空间图形.例如,制作立体几何中的动态空间几何体、动态空间曲线、动态空间曲面等教学课件.有了这个坐标系可以从不同的角度观察图形的真实形状,可以很方便地观察几何体(或曲线或曲面)的正视图、俯视图、侧视图.有助于学生建立空间概念,提高学生的空间想象能力和思维能力,激发学生的学习兴趣,提高课堂效率.     

基于直观想象的空间向量概念教学

空间向量的教学要注重培养学生的空间想象力,在空间向量的概念、规则建立和运用时让直观想象先行,要以对向量的自由性、零向量、投影向量和平面向量概念及其运算为空间想象的逻辑基础,理解平面向量与空间向量的联系,通过直观想象构建几何图形,证明几何定理,理解空间向量解决立体几何问题的本质原理,在空间向量的教学中培养学生的空间观念,发展学生的直观想象素养.     

题高一尺 技高一丈——立体几何三视图、直观图新题“破题法门”

人教版《普通高中课程标准实验教科书(数学必修2)》中,空间几何体的三视图和直观图的内容约2课时,第一课时学习1.2.1中心投影与平行投影和1.2.2空间几何体的三视图;第二课时学习1.2.3空间几何体的直观图,此部分内容是在学习空间几何体的结构特征之后,在尚未学习点、直线、平面的位置关系的情况下教学的,可以为立体几何部分的学习奠定基础,有利于培养学生学习立体几何的兴趣.这块内容的教学目标是让学生能通过"实物模型—三视图—直观图"这样一个相互转化的过程认识空间几何体,是培养学生空间想象能力的有效途径,而只有奠定了空间几何体的认知基础,立体几     

空间向量在立体几何中的初步应用

《全日制普通高级中学教科书》数学 (第二册下Ｂ)课本中 ,对第九章“直线、平面、简单几何体”(简称“9Ｂ”)的内容 ,引进了较新的数学内容———空间向量 ,在进行“9Ｂ”内容的教学实践中 ,我们引导学生将“平面向量”知识引申拓宽到“空间向量” ,较好地完善了向量的知识体系 ,并通过“空间向量”的知识性和工具性这两大特性的教学 ,增强了学生分析问题的能力 ,开阔了学生解决立体几何问题的视野 .现就“空间向量”在立体几何中的初步应用 ,谈谈我们的具体做法 .1　实现由“平面向量”到“空间向量”的自然转化 ,调动学生学习“空间向量”…     

由三道习题浅谈创新思维培养

通过对三道典型题多角度、多方法的研究,比较了求空间立体体积、空间曲面面积和空间曲线弧长的不同方法,既复习了知识点,又培养了学生的创新意识.     

抓关键、破难点、提效率——以空间向量与立体几何专题复习为例

空间向量的引入,既是对平面向量知识的拓展与深化,又是体现向量的工具性作用,特别是在立体几何的学习中,减轻了好多高中学生学习立体几何的难度.但在实际学习中,很多学生由于不会合理建系、空间点的坐标写错、空间角(空间距离)与直线方向向量或平面法向量的关系理解错误等因素导致解答出错.在平时的教学以及复习备考中指导学生抓住这些关键点,可以帮助学生学习好这部分内容,提高复习效率.     

巧用"模型"妙解立几题

立体几何是培养学生空间想象能力的主要载体，提高学生空间想象能力更是立体几何教学的主要任务之一，然而，在教学中到学生具备必要的基础知识和一定的空间想象能力后，如何使学生的空间想象能力，有进一步突破再上一个台阶，是困扰广大教师的一大难题，笔者在教学实践中     

构建空间图形观念，激发数学想象力

<正>立体几何的学习建立在引导学生认识图形的基础之上学习画图、识图、用图，可以激发学生的空间想象能力.然学生学习立体几何的难点在于无法想象图形的不同组合和运动轨迹，影响了学生空间观念的构建.因此，突破立体几何的教学难点，培养学生的空间想象能力长期以来都是中学教学中关注的重点问题.笔者根据教学实践，在研究立体几何教学特点的基础上，探讨如何激发学生的数学想象力，培养空间图形观念.     

Graphensätze für topologische Räume

In generalising a closed graph theorem of Dektjarev [5] we show that each almost closed and uniformly almost continuous relation of a quasi-uniform space to a hypercomplete quasi-uniform space is uniformly continuous. The hypothesis of being almost closed is necessary and actually weaker than the requirement that the relation considered has a closed graph. Since each topological space can be quasi-uniformized, one obtains closed graph theorems for topological spaces.As consequences we get an analogous closed graph theorem for locally uniformly almost continuous relations and a theorem concerning the completeness of the range of each continuous uniformly almost open mapping of a hypercomplete space to a uniform space.Finally we prove a closed graph theorem for relations to locally compact spaces without referring to any quasi-uniformization and thus without assumptions and statements concerning uniformity.     

Join space graphs

A join space is an abstract model for partially ordered linear, spherical and projective geometries. A connected graph is a join space if and only if it is a strong prime convex intersection graph.     

A Conjecture Concerning a Limit of Non-Cayley Graphs

Our aim in this note is to present a transitive graph that we conjecture is not quasi-isometric to any Cayley graph. No such graph is currently known. Our graph arises both as an abstract limit in a suitable space of graphs and in a concrete way as a subset of a product of trees.     

Every connected regular graph of even degree is a Schreier coset graph

Using Petersen's theorem, that every regular graph of even degree is 2-factorable, it is proved that every connected regular graph of even degree is isomorphic to a Schreier coset graph. The method used is a special application of the permutation voltage graph construction developed by the author and Tucker. This work is related to graph imbedding theory, because a Schreier coset graph is a covering space of a bouquet of circles.     

The Borsuk dimension of a graph and Borsuk's partition conjecture for finite sets

Borsuk's partition conjecture for finite subsets of euclidean space is placed in a graph theoretic setting and equivalent graph theoretic conjectures are raised. The Borsuk dimension of a graph is defined and the Borsuk dimensions of various graphs are tabulated.AMS Subject Classification (1985 Revision): 05C99, 05A17     

Logit equilibrium as an approximation of Nash equilibrium

We prove that the graph of the logit equilibrium correspondence is a smooth manifold, which is homeomorphic to the space of payoff functions and uniformly approximates the graph of the Nash equilibrium manifold.     

On two-factors of bipartite regular graphs

The set of two-factors of a bipartite k-regular graph, k>2, spans the cycle space of the graph. In addition, a new non-hamiltonian 3-connected bicubic graph on 92 vertices is constructed.     

On Infinite Cycles I

We adapt the cycle space of a finite graph to locally finite infinite graphs, using as infinite cycles the homeomorphic images of the unit circle S¹ in the graph compactified by its ends. We prove that this cycle space consists of precisely the sets of edges that meet every finite cut evenly, and that the spanning trees whose fundamental cycles generate this cycle space are precisely the end-faithful spanning trees. We also generalize Eulers theorem by showing that a locally finite connected graph with ends contains a closed topological curve traversing every edge exactly once if and only if its entire edge set lies in this cycle space.To the memory of C. St. J. A. Nash-Williams     

Cohomology of GKM fiber bundles

The equivariant cohomology ring of a GKM manifold is isomorphic to the cohomology ring of its GKM graph. In this paper we explore the implications of this fact for equivariant fiber bundles for which the total space and the base space are both GKM and derive a graph theoretical version of the Leray–Hirsch theorem. Then we apply this result to the equivariant cohomology theory of flag varieties.