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Chapter 4 Annotation language for trains 4.2 Reasoning model The simplest form of artificial intelligence (AI) which is generally used in industry is the rule-based system, also known as the expert system. Before we discuss in details what these are, let's take a step back and point out that there are different opinions as to what really constitutes artificial intelligence. Some people, when they use the term AI, are referring to systems which have some ability to learn. That is, the system will improve its performance over time as it gains experience in solving problems, just as a human would. Others, when they use the term AI, are referring just to systems which are capable of exhibiting human-level performance in some very narrow area, but which are incapable of learning or expanding their expertise. Different people are always going to disagree about what AI is, but this is fairly simple form of AI which we want to discuss about right now. A rule-based system is a way of encoding a human expert's knowledge in a fairly narrow area into an automated system. There are a couple of advantages to doing so. One is that the human expert's knowledge then becomes available to a very large range of people. Another advantage is that if you can capture the expertise of an expert in a field, then any knowledge which they might have is not lost when they retire or leave the firm. Rule-based systems differ from standard procedural or objectoriented programs in that there is no clear order in which code executes. Instead, the knowledge of the expert is captured in a set of rules, each of which encodes a small piece of the expert's knowledge. Each rule has a left hand side and a right hand side. The left hand side contains information about certain facts and objects which must be true in order for the rule to potentially fire (that is, execute). Any rules whose left hand side match in this manner at a given time are placed on an agenda. One of the rules on the agenda is picked (there is no way of predicting which one), and right hand side is executed, and then it is removed from the agenda. The agenda is then updated (generally using a special algorithm called the Rete algorithm (Appendix C)), and new rules are selected to execute. This continues until there are no more rules on the agenda. Another reasoning model we can use is BDI agents, BDI stands for BeliefDesire-Intention [35]. A BDI agent is a particular type of bounded rational 35 Video content analysis & aggression detection system for a train environment