STEREOTYPES as an ACTOR Approach Towards Solving the Problem of Procedural Attachment in FRAME Theories

This paper is a spin-off of our work on actors. We have worked out a dictionary for translating between what Minsky et. al. are saying about frames and what we are saying about actors. Using PLASMA [PLANNER-like System Modeled on Actors] we can demonstrate important relationships between the Minsky-frames and the PLANNER-like formalisms. PLASMA does not use the QA-4 context mechanism (Rulifson et. al. 1972). instead it uses explicit tags in assertions to keep track of the state of affairs in various situations. One problem with the QA-4 context mechanism is that the problem solver is forced to attempt to propagate all changes in the situation immediately on a frame shift since otherwise inconsistent information will be inherited from the previous situation. Another problem with QA-4 context meçhanism is that it is sometimes difficult to reason explicitly about various situations using it because situations [frames] are not explicitly part of the assertions and goals. Events that are viewed from several different viewpoints [as in a murder mystery] are difficult to handle. Also it is difficult to retrieve the appropriate prior situations from memory to aid in recognition tasks using QA-4 contexts. However, without the example of the QA-4 contexts to guide us, we could never have realized how to deal with these problems using tagged assertions. The context mechanism in CONNIVER was modeled on the one in QA-4.