17/1/1 © Pearson Education Limited 2002 Artificial Intelligence & Expert Systems Lecture 1 AI, Decision Support, Architecture of expert systems Topic 17

17/1/2 © Pearson Education Limited 2002 Artificial intelligence Emulating human thought processes Making a computer based system behave in the same way as a human Applications –natural language processing - communicate with computer using English-like statements –expert systems, decision support systems –neural networks –retinal scanning

17/1/3 © Pearson Education Limited 2002 Life on Mars?! Evidence of intelligence –traffic management Basic system Not automated Intelligence High? Sophisticated system Automated Intelligence Low?

17/1/4 © Pearson Education Limited 2002 Expert Systems Represent the knowledge & decision making skills of experts Encapsulate the knowledge of experts Provide the tools for acquisition of knowledge Examples –medical diagnosis, legal advice, risk assessment (all require reasoning)

17/1/5 © Pearson Education Limited 2002 Types of Decision

17/1/6 © Pearson Education Limited 2002 Traditional vs Expert Systems Traditional –calculations on data –storage and retrieval of records –credits and debits –orders/deliveries/invoices Expert –medical diagnosis –legal advice

17/1/7 © Pearson Education Limited 2002 Decision Support Systems Degree of structure in problems –1 the data –2 the problem-solving procedures –3 the goals and constraints –4 the flexibility of strategies among the procedures If problem exhibits all four (e.g. credit) –operational system, procedural logic If problem is type 3 –classic expert system solution Others - hybrid solution

17/1/8 © Pearson Education Limited 2002 Role of Expert Body of knowledge Apply, often with incomplete information Deliver solution, with explanation/justification Inform debate, identify own limitations Interact with people requiring expertise Improve knowledge/expertise by learning

17/1/9 © Pearson Education Limited 2002 What is an Expert System? Knowledge base Separate knowledge from particular case Separate knowledge from inference Interactive user interface Output = advice and decisions

17/1/10 © Pearson Education Limited 2002 Domain-specific Knowledge Base Common-sense knowledge –moral, social attitudes, individual interests Procedural knowledge –e.g. Recipes - do this, do that until… Declarative knowledge –e.g. Regulations - if this, then that, unless... –No implied order to finding the solution

17/1/11 © Pearson Education Limited 2002 Architecture of typical expert system

17/1/12 © Pearson Education Limited 2002 Knowledge-acquisition subsystem Entering the domain-specific knowledge Can enter rules directly (next week’s task) Often accomplished using an expert system shell Analogous to rote learning Compare to scientific discovery…

17/1/13 © Pearson Education Limited 2002 Case-specific Knowledge Base facts specific to the particular situation entered by keyboard... or taken from external database… or derived from knowledge base… or gleaned from experience

17/1/14 © Pearson Education Limited 2002 Inference Engine Apply domain-specific knowledge to particular facts of the situation to derive new conclusions Sound inference principles –modus ponens ruleIf it is raining then the ground is wet factIt is raining derived new fact The ground is wet

17/1/15 © Pearson Education Limited 2002 Inference Engine Sound inference principles –modus tollens ruleIf it is raining then the ground is wet factThe ground is not wet derived new fact It is not raining Need a sound inference control strategy –which rules to apply (tutorial exercise)

17/1/16 © Pearson Education Limited 2002 Knowledge base

17/1/17 © Pearson Education Limited 2002 Explanation Subsystem ‘How’ questions –how was the conclusion reached –intermediate solutions ‘Why’ questions –why was a piece of information required Further explanation –what do you mean by… Consultation Trace

17/1/18 © Pearson Education Limited 2002 Simple expert system

17/1/19 © Pearson Education Limited 2002 Simple expert system

17/1/20 © Pearson Education Limited 2002 Practical activities Visit this Web Site... Bookmark it! Download the Practical Activities (filename prolog.rtf)