An Ordering on Goals for Planning- Formalizing Control Information in the Situation Calculus
Fangzhen Lin · 1996
In the situation calculus, plans and legal situations are isomorphic: a situation is legal iff it is the result of executing a plan in the initial situation. This isomorphism is important. It provides a basis on which certain control information in planning can be formalized in the situation calculus. As an application of this isomorphism, we investigate thoroughly a notion of goal ordering, and show its usefulness by applying it in a provably correct way to both linear and nonlinear planning. Introduction One of the features of the situation calculus (McCarthy [14]) is that a situation carries information about its history. For example, from looking at the syntax of the situation do(move(B); do(move(A); S 0 )), we know that it is the result of executing move(B) after move(A) in the situation S 0 . Conversely, given any situation, we obtain a new situation by executing a sequential plan in it. This natural isomorphism between situations and plans makes the situation calculus ideal fo...