Rule-based systems and good representations


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Rule-based systems and good representations

As with Evans' program and Marrian vision, rule-based systems need to make different pieces of information explicit at different times.

When printing rules for their user, what's important is a textual representation that looks like natural language. But an inference engine can't work with this. The internal form of the rules must (for example) allow the inference engine quickly to access the conclusion and each part of the condition. So the system has two options. Either store every rule together with appropriate natural language text, or back-translate the rule to text on output.

Last week, I said that indexing is (in Schank's view) one of the main issues in AI. An example here: in the backward chaining examples, the system had to search the entire knowledge base for rules whose conclusions were pertinent to a given question. E.g. to find, given Resort, all rules with Resort in their conclusion. Efficiency can be raised by making the connection explicit, and building some kind of index which leads you straight from each variable to all the rules which mention it.


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Next: Expert systems and productive laziness
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Jocelyn Ireson-Paine
Wed Feb 14 23:39:25 GMT 1996