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``Branching time'' and ``linear time''


We can tell a story by saying what occurs in each situation. In some situations what occurs is determined by an occurrence action and depends on the fluents holding in the situation. In other situations, we simply provide an axiom, e.g. tex2html_wrap_inline1279 . This is a linear time theory.

However, linear time and branching time are sometimes appropriately used together. Suppose we wish to say that the actor will take the low road or the high road according to which will get him to Scotland first. We can write


Here we have used a branching time criterion for a linear time action.

This is not as elaborate as actual human behavior in which mental events occur calculating which route will lead to earliest arrival.

John McCarthy
Fri Feb 8 17:29:20 PST 2002