np2013_chapter12

facilitate navigation.

what functions are available? what links are live? what content is relevant?
Provide a “map” (implemented in a way that is easy to understand) of where the user has been and what paths may be taken to move elsewhere within the WebApp.



Content

These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 7/e (McGraw-Hill, 2009) Slides copyright 2009 by Roger Pressman.
These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 7/e (McGraw-Hill, 2009) Slides copyright 2009 by Roger Press Design

Where am I? The interface should


What can I do now? The interface should always help the
user understand his current options

Availability

• Binary values are represented by values or ranges of values of physical quantities
Digital System
• A digital system is an interconnection of digital modules. To understand the operation of each digital module, it is necessary to have a basic knowledge of digital circuits and their logical function. • A major trend in digital design methodology is the use of a HDL to describe and simulate the functionality of a digital circuit, it is important that students become familiar with an HDL‐based design methodology.
Octal and Hexadecimal Numbers
Numbers with different bases: Table 1.2.
Octal and Hexadecimal Numbers
Conversion from binary to octal can be done by positioning the binary number into groups of three digits each, starting from the binary point and proceeding to the left and to the right.

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2.1.5 判定问题规约的定义
定义：令和是两个判定问题，如果存在一个 具有如下性能的算法A，可以用多项式的时间，把 问题的实例I转换为问题的实例I，使得I与I的 答案一致，就称以多项式时间规约于，记为 p
举例：问题是：给定一个长度为n整数数组D 和一个整数k判断是否存在D中的一个元素和k相等。 问题是：给定一个长度为m整数数组E和一个整 数k判断是否存在E中的两个元素，其和与k相等。 用于的实例I向的实例I转换的多项式算法A
判定问题举例：给定一个带整数权的有向图G和一 个正整数k，是否存在着一条长度小于k的哈密尔顿回 路？
优化问题举例：给定一个带整数权的有向图G，其 最短路径长度的哈密尔顿长度是多少？
1.3 优化问题向判定问题的转换
判定问题举例：给定一个带整数权的有向图G和一个正整数k， 是否存在着一条长度小于k的哈密尔顿回路？ 优化问题举例：给定一个带整数权的有向图G，其最短路径 长度的哈密尔顿长度是多少？
第12章 NP完全问题
1. NP完全问题概述 2. P类和NP类问题 3. NP完全问题 4. co_NP类和NPI类问题
1. NP完全问题概述
1.1 Church-Turing论题和Cook-Karp论题 1.2 问题分类 1.3 优化问题向判定问题的转换
1.1 Church-Turing论题和CookKarp论题
性质：NP难题包含NP完全问题。但有些NP难题 不是NP完全问题，因为它可能不在NP问题中
3.2 多项式规约关系的传递性定 理
定理：多项式规约关系满足传递性：令、、 是三个判定问题，满足 p ， p ， 则有 p
证明：通过规约关系的定义，必定存在着多项 式算法A和A， A使得的实例I（规模是n） 以多项式时间转换为的实例I，A使得的实 例I以多项式时间转换为的实例I。而A和A的 多项式级别性质使得实例I的规模是n的多项式级 别的。综合起来，的任意实例都能在多项式 级别转换为的实例

E-commerce
business. technology. society.
Third Edition
Kenneth C. Laudon Carol Guercio Traver
Copyright 2007 Pearson Education, Inc.
Slide 12-1
Chapter 12
Slide 12-7
The Growth of B2B E-commerce 2001–2009
B2B e-commerce 2005: $1.5 trillion 2009: $4.11 trillion Net marketplaces growing at faster rate than private industrial networks, but even so, in 2006 private industrial networks still expected to be twice the size of Net marketplaces Not all industries will be similarly affected by B2B ecommerce Computer, automotive, aerospace and defense, and industrial equipment industries likely to move first and fastest to B2B utilization
Types of goods purchased Direct goods: Goods integrally involved in the product process Indirect goods: All other goods not directly involved in production process (sometimes called MRO goods) Methods of purchasing Contract purchasing: Involves long-term written agreements to purchase specified products, with agreed upon terms and quality Spot purchasing: Involves purchase of goods based on immediate needs in larger marketplaces that involve many suppliers