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Branch Merging

It is possible to construct a plan in which branches split and then reunite. For instance, consider the Western/Ashland plan once again. The context in which the goal to get to Evanston arises might be an obligation to deliver a toast at a dinner to be held in an Evanston restaurant. The contingency due to uncertainty about traffic on Western Avenue would in this case seem to affect only the portion of the plan concerned with getting to Evanston; it probably has little bearing on the wording of the toast, the choice of wine, and so on. The most natural way to frame this plan might thus be to assume that regardless of which contingency is carried out, the planner will eventually arrive at a certain location in Evanston, and from that point a single plan will be developed to achieve the final goal.

Constructing the plan in this way would result in a more compact plan description, and might thus reduce the effort needed to construct the plan by avoiding, for example, the construction of multiple copies of the same subplan. We are considering methods by which branch re-merging might be achieved, but all the methods we have considered so far seem to complicate the planning process considerably.

Louise Pryor <>;
Last modified: Mon Mar 18 18:06:36 1996