Also included in the database are the logical I/O buffers. The BB* representation is uniform and declarative, and it provides universal access. The generality of the network representation can also incorporate meta-knowledge, through its representation of plans.
However, the BB* representation's use of knowledge sources deviates from the more STRIPS-like styles. While knowledge sources do have pre-conditions, they are not restricted to simple add/delete clauses. In fact, knowledge sources contain arbitrary pieces of code, to be executed upon pre-condition matches. Since this code is unbounded in the amount of time required, a knowledge source can not be granted total control of execution. This would violate the requirement for guaranteed latencies. However, the simple precondition-matching required for activation of a knowledge source does permit fast access to knowledge.
A sample network (from Guardian) is also available.
