Expert System - Knowledge Acquisition PDF

EXPERT SYSTEM – Knowledge Acquisition ESC 4506 Knowledge???  (i) expertise, and skills acquired by a person through experience or education; the theoretical or practical understanding of a subject,  (ii) what is known in a particular field or in total; facts and information, or...

EXPERT SYSTEM – Knowledge Acquisition ESC 4506 Knowledge???  (i) expertise, and skills acquired by a person through experience or education; the theoretical or practical understanding of a subject,  (ii) what is known in a particular field or in total; facts and information, or  (iii) awareness or familiarity gained by experience of a fact or situation. (Oxford English Dictionary) Knowledge Acquisition  includes the elicitation, collection, analysis, modelling and validation of knowledge for knowledge engineering and knowledge management projects.  the transformation of knowledge from the forms in which it exists into forms that can be used in a knowledge based system (KBS). Knowledge acquisition  Transferring problem-solving expertise from a knowledge source and transforming it into computer program  Most important, most difficult part and most time consuming Knowledge Types  procedural knowledge (of what to do or how to do it)  is about rules, methods, procedures etc.  declarative knowledge (of what is and what is not)  is about facts, concepts, assertions and so on.  Rulesand methods are usually specific to particular tasks, while facts and concepts can often be more generic. Issues in Knowledge Acquisition (CHALLENGES)  Most knowledge is in the heads of experts  Experts have vast amounts of knowledge  Experts have a lot of tacit knowledge  They don't know all that they know and use  Tacit knowledge is hard (impossible) to describe  Expertsare very busy and valuable people  Each expert doesn't know everything  Knowledge has a "shelf life" Knowledge  Tacit knowledge is knowledge that is difficult to be transferred to another person by means of writing down or verbalizing it. While tacit knowledge appears to be simple, it has far reaching consequences and is not widely understood.  With tacit knowledge, people are not often aware of the knowledge they possess or how it can be valuable to others. Effective transfer of tacit knowledge generally requires extensive personal contact and trust.  Tacit knowledge is not easily shared. Tacit knowledge consists often of habits and culture that we do not recognize in ourselves. The tacit aspects of knowledge are those that cannot be codified, but can only be transmitted via training or gained through personal experience. Tacit knowledge has been described as “know-how” -- as opposed to “know-what” (facts), “know-why” (science), or “know-who” (networking). Knowledge  Explicit knowledge is knowledge that easy to communicate.  Is a articulated knowledge, expressed and recorded as words, numbers, codes, mathematical and scientific formulae, and musical notations. Explicit knowledge is easy to communicate, store, and distribute and is the knowledge found in books, on the web, and other visual and oral means. Opposite of tacit knowledge. Requirements for KA Techniques Because of these issues, techniques are required which:  Take experts off the job for short time periods  Allow non-experts to understand the knowledge  Focus on the essential knowledge  Can capture tacit knowledge  Allow knowledge to be collated from different experts  Allow knowledge to be validated and maintained KA Techniques  Protocol-generation techniques include various types of interviews (unstructured, semi-structured and structured), reporting techniques (such as self-report and shadowing) and observational techniques  Protocol analysis techniques are used with transcripts of interviews or other text-based information to identify various types of knowledge, such as goals, decisions, relationships and attributes. This acts as a bridge between the use of protocol-based techniques and knowledge modelling techniques.  Hierarchy-generation techniques, such as laddering, are used to build taxonomies or other hierarchical structures such as goal trees and decision networks. KA Techniques  Matrix-based techniques involve the construction of grids indicating such things as problems encountered against possible solutions. Important types include the use of frames for representing the properties of concepts and the repertory grid technique used to elicit, rate, analyse and categorise the properties of concepts.  Sorting techniques are used for capturing the way people compare and order concepts, and can lead to the revelation of knowledge about classes, properties and priorities. KA Techniques  Limited-information and constrained- processing tasks are techniques that either limit the time and/or information available to the expert when performing tasks. For instance, the twenty- questions technique provides an efficient way of accessing the key information in a domain in a prioritised order.  Diagram-based techniques include the generation and use of concept maps, state transition networks, event diagrams and process maps. The use of these is particularly important in capturing the "what, how, when, who and why" of tasks and events. Typical Use of KA Techniques  Conduct an initial interview with the expert in order to (a) scope what knowledge is to be acquired, (b) determine what purpose the knowledge is to be put, (c) gain some understanding of key terminology, and (d) build a rapport with the expert. This interview (as with all session with experts) is recorded on either audiotape or videotape.  Transcribe the initial interview and analyse the resulting protocol. Create a concept ladder of the resulting knowledge to provide a broad representation of the knowledge in the domain. Use the ladder to produce a set of questions which cover the essential issues across the domain and which serve the goals of the knowledge acquisition project.  Conduct a semi-structured interview with the expert using the pre-prepared questions to provide structure and focus. Typical Use of KA Techniques  Transcribe the semi-structured interview and analyse the resulting protocol for the knowledge types present. Typically these would be concepts, attributes, values, relationships, tasks and rules.  Represent these knowledge elements using the most appropriate knowledge models, e.g. ladders, grids, network diagrams, hypertext, etc. In addition, document anecdotes, illustrations and explanations in a structured manner using hypertext and template headings.  Use the resulting knowledge models and structured text with contrived techniques such as laddering, think aloud problem-solving, twenty questions and repertory grid to allow the expert to modify and expand on the knowledge already captured. Typical Use of KA Techniques  Repeat the analysis, model building and acquisition sessions until the expert and knowledge engineer are happy that the goals of the project have been realised.  Validate the knowledge acquired with other experts, and make modifications where necessary. Knowledge acquisition - example  Phase I Detailed text analysis of textbooks & manuals Used as core knowledge  Phase II Interviews with domain experts & observations Used to reinforced, refine and expand the core knowledge  Phase III Text analysis of research publications Used to reinforced, refine and expand the core knowledge