Implicit in the discussions about island processing and soundness is the concept of optimization. Optimization refers to the fact that all of the dependencies are pre-analyzed, and that every time a rule is failed or an island rule created, all of the rules that must be failed as a result are known immediately. This eliminates the need to be constantly looking at the contents of the rules. More importantly, it eliminates the need of incrementally propagating constraints every time a rule is instantiated. Since all the effects are known ahead of time, no constraint propagation is necessary during the actual processing. Thus, after optimization, the system is reduced to a knowledge-free tree traversal.