Internet services The Internet can be used in in different ways: for distributing and retrieving information, for one-to-one, one-to-many and many-to-many communication, and for the access services. Accordingly, there are different services on offer. The most important of these are listed below. Telnet FTP (File Transfer Protocol) Electronic Messaging (E-Mail) World Wide Web (WWW) Bulletin Board Systems (BBS) Electronic Data Interchange (EDI) Internet Relay Chat (IRC) Multiple User Dimensions (MUDs) Gopher

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Expert system Expert systems are advanced computer programs that mimic the knowledge and reasoning capabilities of an expert in a particular discipline. Their creators strive to clone the expertise of one or several human specialists to develop a tool that can be used by the layman to solve difficult or ambiguous problems. Expert systems differ from conventional computer programs as they combine facts with rules that state relations between the facts to achieve a crude form of reasoning analogous to artificial intelligence. The three main elements of expert systems are: (1) an interface which allows interaction between the system and the user, (2) a database (also called the knowledge base) which consists of axioms and rules, and (3) the inference engine, a computer program that executes the inference-making process. The disadvantage of rule-based expert systems is that they cannot handle unanticipated events, as every condition that may be encountered must be described by a rule. They also remain limited to narrow problem domains such as troubleshooting malfunctioning equipment or medical image interpretation, but still have the advantage of being much lower in costs compared with paying an expert or a team of specialists.

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