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task, but rather that it is the way in which these rules and other representational formalisms are themselves represented that is the limiting factor.
     At first a simple rule-base is relatively transparent, especially if properly documented. Certainly such systems were easier to comprehend than procedural code and were subsequently easier to update and amend. As such rule bases became larger and more complex however, a simple syntax error, perhaps only involving one word, could prevent them from operating correctly. The complexity of these rulesets also meant that it was difficult to get an overview of what was intended, thus impeding their maintenance and extension.

A Picture is Worth a Thousand Words
     The problem of rulebase comprehensibility, I would argue, is the fact that we have primarily represented knowledge using text based structures rather than visual ones. No matter how close to natural language a knowledge representation language is, you cannot see at a glance what a complex system is trying to do.

Visual Rule Generation
     Rule generation via a graphical interface is a hot topic right now, with offerings from a number of companies small and large. This is being driven in part by current interest in so-called 'business rules management' which is arguably a reawakening of the KBS paradigm we mentioned earlier.
     London based Logic Programming Associates is an appropriate company to enter this market as it has been producing rule-based software since the mid 1980s. Its latest product, VisiRule, enables rule-based systems to be automatically generated from a flowchart drawn on the screen.

Consider the following business rule (Ross 2003):

Rule: An order must be credit-checked if any of the following is true:

     * The order total is more than $500
     * The outstanding balance of the customer's account plus           the order amount is more than $600
     * The customer's account is not older than 30 days
     * The customer's account is inactive
     * The customer is out of state

Figure 1

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