On A* as a Special Case of Ordered Search

The A* admissibility and optimality proofs presented to date have been based on overly restrictive assumptions about the relationship between real and estimated costs. This paper shows that idealism, accuracy and selectivity, properties hitherto thought to be unique to A*, are in fact common to all ordered searches, and do not require the evaluation function / = g+ h traditionally assumed. Consequently, much of A* theory can be greatly simplified.