There are a number of background papers on planning, scheduling, and control that are relevant to the APA architecture. These papers include descriptions of the ERE architecture, which is the precursor and a generalization of the APA architecture, and of Situated Control Rules which is the precursor of the ATIS 116 statement used to express schedules for the telescope.
Independent competence helps to ensure that the telescope keeps collecting data.
The APA includes a scheduler that provides a highly-optimized schedule for the telescope controller. If communications fail, or if the APA should unceremoniously expire, the telescope controller proceeds by using heuristic dispatch scheduling. The controller has a rudimentary scheduling competence independent from the optimizing scheduler. Reaction-first search uses an existing dispatch policy as guidance for a more sophisticated search engine. This is a very useful guarantee in practice, since we can be sure that the APA's scheduler can only improve upon the existing performance of the telescope controller's heuristic dispatcher.