Preferences
Preferences
In addition to adding regular working memory elements, the elaboration
phase also adds special information about what action should be taken
next. This information is called a preference. Preferences allow the
architecture to specify both that an action could be taken (without
actually taking it) and that the action should be taken. A
preference always refers to the adoption of some particular object in some
position in the context stack and takes
one of the following values:
-
Acceptable
The object is acceptable for a particular context slot.
-
Reject
The object is not acceptable for a particular context slot.
-
Relative Preference
The object is better (or worse) than some other object.
-
Absolute Preference
The object is the best (or worst) choice for some particular context slot.
-
Indifferent
Two (or more) objects are indifferent to one another for a choice in a
mutual context slot.
The generation of preferences is assumed to be complete for any decision
cycle. This is an example of a
closed world
assumption
in Soar -- everything that could be brought to bear was. Additionally, the
preferences need not be unique. For instance, there
can be more than one best
preference or a conflict when preferences are generated for two
objects that indicates that each is better than the other. The
decision procedure
acts on the preferences that were generated
during the preceding
elaboration phase.
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