Chapter 13 Artificial Intelligence Introduction n n Artificial

Chapter 13 Artificial Intelligence

Introduction n n Artificial intelligence (AI) is the part of computer science that attempts to make computers act like human beings. Turing test:

A Division of Labor n Three categories of tasks: • Computational tasks: n n Adding numbers, sorting, searching Calculating the trajectory for the space shuttle • Recognition tasks: n n Recognizing your best friend Understanding the spoken word • Reasoning tasks: n n Planning what to wear today Deciding company’s strategic directions

Human and Computer Capabilities

Knowledge Representation Methods n n Natural language Formal language Pictorial Graphical: e. g. , semantic net

Requirements n n Adequacy: the representation method must be adequate to capture all of the relevant knowledge. Efficiency: we want the representation form to be minimalist. Extendability Appropriateness

Recognition Tasks n n Connectionist architecture: formed by large number of simple “processors” (neurons) with multiple interconnections. A neuron:

Artificial Neural Networks n n n n Simulate the connectionist architecture of human brain Applied to recognition task A neural network for comparing two characters What happens when two As are presented? One A and one Y? Perceptrons Back-propagation algorithm

Reasoning Tasks n Intelligent searching • Decision tree for sequential search • Decision tree for binary search n n n Best-first search Means-end analysis Search the Internet: spider

Intelligent Agent n n A software technology designed to interact collaboratively with a user somewhat in the mode of a personal assistant. Examples: • Desktop office software Office小幫手 • Personalized Web search engine • Buying and selling agents • Electronic travel agents

Expert Systems n n n Rule-based systems Knowledge-based systems Contains two components: • A knowledge base: a set of facts about the subject matter • An inference engine: a mechanism for selecting the relevant facts and for reasoning from them in a logical way

The Reasoning Process n n Modus ponens: method of assertion Inference engines for rule-based system can proceed in: • Forwarding chaining: begins with assertions and tries to match those assertions to the “if” clauses of rules, thereby generating new assertions. • Backward chaining: begins with a proposed conclusion and tries to match it with the “then” clauses of rules. It then looks at the corresponding “if” clauses and tries to match those with assertions.

Software Components of TCP/IP n Application Layer • Examples: SMTP (mail), Telnet, FTP, Rlogin, NFS, … n Transport Layer • The transport uses two protocols, UDP and TCP. UDP which stands for User Datagram Protocol does not guarantee packet delivery and applications which use this must provide their own means of verifying delivery. TCP does guarantee delivery of packets to the applications which use it. n Network Layer • The network layer is concerned with packet routing and used low level protocols such as ICMP, IP, and IGMP. In addition, routing protocols such as RIP, OSPF, and EGP will be discussed. n Link Layer • The link layer is concerned with the actual transmittal of packets as well as IP to Ethernet address translation. This layer is concerned with Arp, the device driver, and Rarp.