查询词典 algebraic closure operator

It shows the effectiveness and practicability of the approach to prove algebraic identies with combinatorial analysis .

说明了用组合分析方法证明代数恒等式的有效性和实用性。

Today, the main means of the study of the 3-manifold are the algebraic method, geometrical method,and combinatorial method.

目前，关于三维流形理论的研究主要有代数方法，几何方法和组合方法。

Algebraic semantics ; Barcan formula ; Kripke's relational semantics ; nested domains ; Kripke's special semantic ; completeness theorem

代数语义； Barcan－公式； Kripke的关系语义；嵌套论域；狭义Kripke语义；完全性定理

To regulate policy composition and guarantee its correctness, an algebraic model called APoCA (attribute-based access control policy composition algebra) is proposed for composing access control policy. In APoCA, an authorization relation between entities is described at the attribute level. APoCA fertilizes the existing formal frameworks by taking into account the computation of attribute values.

为了规范策略合成和保障策略合成正确性，基于属性刻画了实体间的授权关系，通过属性值的计算结构扩展了现有的策略合成形式化框架，建立了新的基于属性的策略合成代数模型APoCA(attribute-base access control policy composition algebra)。

Liber Abaci emphasizes summed-up algorithm, but does not pay attention to the form of propositions derived, and it mainly reflects the tendency of practical algorithms, such as principal method from India and the algebraic knowledge from the Arab. In Liber Abaci it is found some problems similar to ancient Chinese mathematics like pursuit problems, drainage problems, business problems, hundred fowls problems, remainder problems, indeterminate problems, as well as some Algorithm—fraction addition and subtraction,the compound rule of three, the method Elchataym and the method of Excess and Deficit, and so on.

在系统梳理《计算之书》数学内容过程中，笔者发现《计算之书》中存有与中国古代数学中相似的实用算题，如：追及问题、排水问题、经商问题、百鸡问题、剩余问题、不定问题等，以及和中算一致的算法：分数算法、多率法和重今有术、第二类"Elchataym算法"和盈不足术等。

Keywords: ADT, Algebraic specifications, Conditional equation, Correctness

如果能获得简明的条件描述，那么就容易写出条件方程。

This article takes the teaching of conic sections as an example. By designing worksheets, teachers can introduce the historical material about conic sections to students. By way of using Apollonius' definition of parabola, ellipse and hyperbola, teachers can introduce the geometric aspect of "conic section" to students. By using the concept of " latus rectum " in Conics , we can connect "conic sections"-- representation of geometrical aspect, with "the equation of conic sections"-- representation of algebraic aspect to improving insufficiency of text books.

同时本文也试著从历史文本中寻找材料，简单举例说明数学教师可以如何应用这些史料在几何单元教学上，例如三角函数的正余弦定理，最后再以圆锥曲线的正焦弦为例，说明如何利用数学史料於此单元的教学，尤其是阿波罗尼斯的《锥线论》中对圆锥曲线的3个命题，将此3个命题的内容与意涵，尤其是正焦弦在圆锥曲线的几何意义上所扮演的角色，将其适当地融入教学中，将可使学生真正学习圆锥曲线的几何知识，而不再只是代数形式的几何知识。

Chapter 1 briefs the relation between invariance and computer vision and summarizes the research and application of invariance in computer vision. Chapter 2 first derives the transformations of three camera models, then makes the correpondences between the models and three typical geometrical transformation groups by analysing the transformations respectively. The correspondences supply the theoretical basis for applying geometrical invariants to resolve the problems of computer vision. In Chapter 3, we describe the geometrical invariant theory and prove some geometrical invariants of coplanar points, lines or conics by algebraic method. In order to use the invariants of conic pairs to describe general 2D shapes, we discuss the perspectively invariant representation of planar curves using conies in detail. A system consisted of two TMS320C25 and based on moment invariants is introduced in Chapter 5. The system can recognize more than 30 different shapes of object model or more than 10 plane models with similar shape in real time.

第一章简述了不变性与计算机视觉的关系，以及计算机视觉中的不变性研究和应用概况；第二章推导了计算机视觉中常用三种投影模型的变换关系，通过对这三种变换关系的分析，分别建立了这三种投影模型和几何学中的三种变换群之间的一一对应关系，为几何不变性在计算机视觉中的应用提供了理论基础；在第三章中，我们介绍了几何不变性的理论，并且用代数方法证明了共面点、直线、二次曲线的几何不变量和射影不变量；为了把二次曲线的不变量用于一般二维形状描述，在第四章中我们详细地讨论了用二次曲线实现一般平面曲线的透视不变性表示的方法；第五章介绍了用两片TMS320C25构成的、基于不变矩形特征的运动目标实时识别系统。

We give a purely algebraic method to add uniton numbers for harmonic maps from a simply connected domain into the unitary group.

对于从单连通区域到酉群的调和映射，我们给出了一个增加酉子数的纯代数方法。

It is proved that the algorithm is convergenced for arbitrary consistent systems of linear algebraic equations.

本文利用行处理法[2～4]和分治策略[5]探讨这一问题。将任意的n×m阶线性代数方程组=bi，∥αi∈R1×m∥i=1，2，…，n。

Researches reveal that students who suffer from corporal punishment tend to resort to violence in their future life.

研究表明遭受过肉体惩罚的孩子倾向于在他们今后的人生中使用暴力。

Total sugar of sarcocarp and chlorophyll of pericarp increased firstly, and then decreased afterward along with altitude; Titratable acidity, ascorbicacid and anthocyanin of pericarp were increased along with altitude; The content of protein increased firstly and decreased afterward along with altitude; Carotenoid of pericarp were decreased along with altitude.

果肉总糖和果皮叶绿素含量随海拔高度升高先升高后降低；可滴定酸、维生素C和果皮花青苷含量均随海拔升高而升高；蛋白质在1720m处最大，1420m处最小；果皮类胡萝卜素随海拔升高而降低。