Page 125 - Intelligent Communication Systems

104 INTELLIGENT COMMUNICATION SYSTEMS
connects the call to Mr. Tanaka. With intelligent inquiry service, the system, when
asked, say, "Please let me know of a cut-rate clothing shop in San Francisco," sup-
plies the requested phone number.
With all these services, the system interprets the inquiry from a client and
returns an answer. There are a variety of requirements from clients, expressed in
a variety of utterances. It is difficult for a computer to understand every such utter-
ance. Predicate logic is one way to handle these problems, and predicate logic is
appropriate not only for human beings but also for computers. The representations
of knowledge, such as production rales and semantic networks, and the inference
machine, also useful for telecommunications, are described in this chapter, as are
prepositional logic and predicate logic.

10.1 APPLICATION OF PRODUCTION RULES
TO TELECOMMUNICATIONS

Production rules are used to describe the maintenance and operation of a communi-
cation system. A production rule (PR) is defined as follows:

IF conditional clause, THEN action clause.

An execution algorithm for a PR is shown in Figure 10.1. Here's a strategy
for executing a production rule:

(1) A production rale that is matched to a variable in working memory
(WM) is chosen.
(2) A production rale with the longest conditional clause is chosen.
(3) All of the production rales that are matched to the variables in WM are
chosen.
(4) All of the production rales that are matched to the variables in WM
except the production rales that have been chosen so far are selected.

Example 1—Execution of Production Rules:
(1) In Figure 10.2, "Pork" and "Cabbage" are in WM.
(2) Production rales PI and P5, which are matched to "Pork" and
"Cabbage," are chosen.
(3) P5 is selected first and executed. After execution, "Vegetable" is
derived and stored in WM.
(4) P6, which is matched to "Vegetable," is chosen.
(5) P6 is executed. After execution, "Ted dislikes" is stored in WM. No
production rale matched to "Ted dislikes" is found, so execution is
complete and the conclusion is that "Ted dislikes cabbage."
(6) PI is executed and "Meat" is stored in WM.