Page 53 - DCAP310_INTRODUCTION_TO_ARTIFICIAL_INTELLIGENCE_AND_EXPERT_SYSTEMS

Unit 3: Representation of Knowledge

helpful to hold meetings away from the expert’s workplace. Another possibility is to hold Notes
meetings after work hours and on weekends. At least initially, audiotape recordings ought to be
made of the interviews because often times notes taken during an interview can be incomplete
or suggest inconsistencies that can be clarified by listening to the tape. The knowledge engineer
should also be alert to fatigue and limit interviews accordingly. In early interviews, the format
should be unstructured in the sense that discussion can take its own course.

Did u know? The knowledge engineer should resist the temptation to impose personal
biases on what the expert is saying.
During early discussions, experts are often asked to describe the tasks encountered in the domain
and to go through example tasks explaining each step. An alternative or supplemental approach
is simply to observe the expert on the job solving problems without interruption or to have the
expert talk aloud during performance of a task with or without interruption. These procedures
are variations of protocol analysis and are useful only with experts that primarily use verbal
thought processes to solve domain problems. For shorter term projects, initial interviews can be
formalized to simplify rapid prototyping. One such technique is a structured interview in which
the expert is asked to list the variables considered when making a decision. Next the expert is
asked to list possible outcomes (solutions) from decision making. Finally, the expert is asked to
connect variables to one another, solutions to one another and variables to solutions through
rules.
A second technique is called twenty questions. With this technique, the knowledge engineer
develops several scenarios typical of the domain before the interview. At the beginning of the
interview, the expert asks whatever questions are necessary to understand the scenario well
enough to determine the solution. Once the expert begins the questions, the expert is asked to
explain why each question is asked. When the interviewer perceives a rule, he interrupts and
restates the rule to ensure that it is correct.
A third technique is card sorting. In this procedure, the knowledge engineer prepares a stack of
cards with typical solutions to problems in the domain. The expert is asked to sort the cards
according to some characteristic important to finding solutions to the problem. After each sort,
the expert is asked to identify the sorting variable. After each sort, the expert is asked to repeat
the process based on another variable.

Notes During interviews, it may be helpful to work at a whiteboard to flexibly record
and order the exact phraseology of rules or other representations. It may also be helpful to
establish recording conventions for use such as color coding different aspects of a rule and
using flags to note and defer consideration of significant but peripheral details. Structured
interviews should direct the course of a meeting to accomplish specific goals defined in
advance.

Example: Once a prototypic knowledge base is developed, the expert can be asked to
evaluate it line by line. Other less obvious structures can be imposed on interviews, such as
asking the expert to perform a task with limited information or during a limited period of time.
Even these structured interviews can deviate from the session’s intended goals. Sometimes such
deviations show subtleties in the expert’s procedures and at other times the interview simply
becomes sidetracked, requiring the knowledge engineer to redirect the session.

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