Planning with Effectively Propositional Logic

We present a fragment of predicate logic which allows the use of equality and quantification but whose models are limited to finite Herbrand interpretations. Formulae in this logic can be thought as syntactic sugar on top of the Bernays-Schonfinkel fragment and can, therefore, still be effectively grounded into a propositional representation. We motivate the study of this logic by showing that practical problems from the area of planning can be naturally and succinctly represented using the added syntactic features. Moreover, from a theoretical point of view, we show that this logic allows, when compared to the propositional approach, not only more compact encodings but also exponentially shorter refutation proofs.