The PEACTIDM model (as laid out in section 5.3.2 of Allen Newell's book Unified Theories of Cognition, and as interpreted by us) is a model for immediate behavior which provides one hypothesis for a way to model extensive interaction with the outside world. Because this model appears to work well with chunking, and accounts for certain timing data, it seemed appropriate to use it in revising the NTD simulation to run with learning on.

We have tried to be faithful to this model by forcing all operators that are selected in the top space to fit into one of the operator categories outlined by this work. Specifically, there are four kinds of operators, which appear in various ways within our model:

Each of these operators has a specific, reasonably well delineated set of functions, and all operators fall into one of these categories. Because all interaction with the world is being done from the top space, non-contemporaneous chunking and other difficult I/O problems are much more readily avoided.