Miracles in formal theories of action
The paper provides a formalization of reasoning about actions. It is a research note reporting on a development of Lifschitz's approach based on situation calculus and circumscription. The problem is how to formalize a (more complex with respect to temporal projection) form of reasoning about actions. It consists, roughly speaking, in determining values in past situations. The problem could be solved in a straightforward way using an implicit assumption that there are no events happening concurrently with the actions that are being carried out. This assumption is relaxed - it is treated as a default principle. If this assumption is inconsistent with the given facts the possibility of some additional events contributing to the properties of the new situation is assumed. It could be said that a miracle happened in the previous situation. A formal solution of the problem is presented. The solution is checked on two examples.
scientific article; zbMATH DE number 4128433