In 1736， Euler founded Graph Theory by solving the Konigsberg seven-bridge problem. It has been more than two hundred years till now. Graph Theory is the core content of Discrete Mathematics， and Discrete Mathematics is the theoretical basis of Computer Science and Network Information Science. This book vulgarly introduces in an elementary way some basic knowledge and the primary methods in Graph Theory. Through some interesting mathematic problems and games the authors expand the knowledge of Middle School Students and improve their skills in analyzing problems and solving problems.

《世界数学奥林匹克经典》由数学竞赛命题委员会主席和数学邀请赛命题委员会主席等专家共同编著。《世界数学奥林匹克经典》自出版后就深受广大使用者的好评。《世界数学奥林匹克经典》为英文版本。

Probability theory is an important branch of mathematics， with wide applications in many fields. It is not only a required course for students of science and technology at universities， but also has entered into Chinese high school textbooks now.This little book will， in an interesting problem-solving way， explain what probability theory is： its concepts， methods and meanings; particularly， two important concepts-probability and mathematical expectation （briefly expectation）-are emphasized. It consists of 65 problems， appended by 107 exercises and their answers.As an extracurricular book providing supplement materials to and advanced knowledge beyond high school textbooks， its aim is to stimulate study interests of students and broaden their knowledge horizons. Some problems were given a little deeper treatment， which can be used as topics for explorative study; and they can also be skipped temporarily if a reader feels difficult to understand them at the beginning.It is presupposed that our readers possess a knowledge of permutations and combinations， and it would be better if they have already learned basic probability theory from their textbooks. However， in order to avoid repetition， we mention as little as possible the contents of textbooks.It is a random event that this little book reaches you. I do not know how much the probability that this event occurs is. However， it is my expectation that this book could reach you， which means that you have a special affinity with it.

《世界数学奥林匹克经典》由数学竞赛命题委员会主席和数学邀请赛命题委员会主席等专家共同编著。《世界数学奥林匹克经典》自出版后就深受广大使用者的好评。《世界数学奥林匹克经典》为英文版本。

本书的第一篇论述了算术的性质，包括数字的性质、算术语言、算术推理。其中，重点介绍了算术推理的本质。第二篇讲述了分解法、合成法。第三篇论述了比较法。分解法、合成法、比较法是算术的三合一基础，这种新概论得到公众的普遍认可。第四篇对分数进行了充分讨论，展示了分数的性质以及它们和整数的逻辑关系。同时，也充分讨论了小数的起源、运算，循环小数的运算和原则等。第五篇讲述了名数的性质。文中认为名数是连续量的数值表示，其中一些假设单位当作一种度量。这样引出了对名数的一个新定义，同时也陈述了不同种类名数的起源，并讲述了很多关于它们的有趣故事。

内容简介奥数并不是数学解题技术的集合，而应是增进数学教育的一个体系，这是作者一直以来的一个理念。一个优秀学生要能灵活并严谨地思考问题。逻辑推理能力只是一个基本功，还要有能从直觉出发直击问题核心的能力。要能通过预测、归纳、想象、构造和设计来实现自己的创新性想法，并能在具体与抽象之间随意切换。这些都是本书作者希望通过奥数训练来让学生提升的能力。作者原是复旦大学数学系教授，后移居新加坡。这套书是根据作者在新加坡维多利亚初级学院、华侨中学、南洋女中、德明政府中学等名校教授了几十年的数学奥林匹克培训课程讲义改编而成的。其范围和深度不仅涵盖和超出了通常的数学教学大纲，而且还介绍了现代数学中的各种概念和方法。整套教程共4卷，初中、高中各2卷，每一卷包含15讲，每讲都以概念、理论和方法为核心，再举8―10个例题来进一步解释和丰富这些核心思想并表明它们的应用，每一讲还留有适当数量的题目以供读者练习和测试，这些题目选自中国、美国、俄罗斯、德国、英国、爱尔兰、罗马尼亚、匈牙利、保加利亚、波兰、白俄罗斯、波罗的海地区、摩尔多瓦、克罗地亚、斯洛文尼亚、希腊、意大利、巴尔干半岛、土耳其、新加坡、日本、韩国、越南、泰国、印度、伊朗、澳大利亚、新西兰、加拿大、哥伦比亚等世界各地的数学奥林匹克竞赛真题。本套书可作为数学奥数课程的教材，也可供优秀学生自学使用，或作为相关教师和研究人员的参考书。本套书的另一大特点是用英文写成，帮助读者了解数学研究是如何去专业表达的，与国际接轨，助力更多的年轻读者在未来走上科学研究之路。

研究金属粉尘爆燃及抑制机理，对保障涉金属粉尘工业生产安全具有重要意义。《典型金属粉尘爆燃特性及抑制机理》通过理论分析和实验研究相结合的方法，对典型金属粉尘爆炸特性及抑制机理进行研究，主要包括典型金属粉尘爆炸火焰阵面结构、火焰阵面传播行为、火焰微观精细结构特征等；不同阶段爆炸压力的演变规律；惰性粉体对典型金属粉尘爆炸抑制机理；以天然多孔材料为载体，以碳酸氢钠、磷酸二氢钾等化学活性粉体作为负载颗粒，制备具有物理与化学高效协同抑爆效应的新型复合粉体抑爆剂，揭示复合粉体抑爆剂抑制典型金属粉尘爆炸的机理。

This book consists of three parts： fundamental knowledge， basic methods and typical problems. These three parts introduce the fundamental knowledge of solving combinatorial problems， the important solutions to combinatorial problems and some typical problems with often-used solutions in the high school mathematical competition respectively.In each chapter there are necessary examples and exercises with solutions. These examples and exercises are of the same level of difficulty as the China Mathematical League Competitions which are selected from mathematical competitions at home and abroad in recent years. Some test questions are created by the author himself and a few easy questions in China Mathematical Olympiad （CMO） and IMO are also included. In this book， the author pay attention to leading readers to explore， analyze and summarize the ideas and methods of solving combinatorial problems. The readers' mathematical concepts and abilities will be improved remarkably after acquiring knowledge from this book.

Number theory is an important research field in mathematics. In mathematical competition， problems of elementary number theoryoccur frequently. This kind of problems uses little knowledge and has lots of variations. They are flexible and diverse.In the book we introduce some basic concepts and methods in elementary number theory via problems in mathematics competition.We hope that readers read the book with paper and pencil， and try to solve them by themselves before they read the solutions of examples.Only in this way can they really appreciate the tricks of problem solving.

Mathematical induction is an important method used to prove particular math statements and is widely applicable in different branches of mathematics， among which it is most frequently used in sequences.This book is rewritten on the basis of the book Methods and Techniques for Proving by Mathematical Induction ， and is written with an understanding that sequences and mathematical induction overlap and share similar ideas in the realm of mathematics knowledge. Since there are a lot of theses and books related to this topic already， the author spent quite a lot of time reviewing and refining the contents in order to avoid regurgitating information. For example， this book refers to some of the most updated Math Olympiad problems from different countries， places emphasis on the methods and techniques for dealing with problems， and discusses the connotations and the essence of mathematical induction in different contexts.The author attempts to use some common characteristics of sequences and mathematical induction to fundamentally connect Math Olympiad problems to particular branches of mathematics. In doing so. the author hopes to reveal the beauty and joy involved with math exploration and at the same time， attempts to arouse readers' interest of learning math and invigorate their courage to challenge themselves with difficult problems.