Equational Logic Programming Actions, and Change

Recently three approaches for solving planning problems deductively were proposed each of which does not require to state frame axioms explicitly. These approaches are based on the linear connection method, an equational logic programming language, and on linear logic. In this paper, we briefly review these approaches and show that they are equivalent. Moreover, we illustrate that these approaches are not only restricted to deductive planning, but can be applied whenever actions are to be modelled in logic. We show that the approaches essentially amount on building predicates over the data structure multiset. Such multisets are interpreted as resources, which are consumed and produced by actions. We give a minimal and complete unification algorithm for the equational theory which defines the multisets. Finally, we discuss possible extensions of the equational logic programming approach.