On Some Properties of Forgetting in ASP

Many approaches for forgetting in Answer Set Programming (ASP) have been proposed in recent years, in the form of specific operators, or classes of operators, following different principles and obeying different properties. Whereas each approach was developed to somehow address some particular view on forgetting, thus aimed at obeying a specific set of properties deemed adequate for such view, only a recently published comprehensive overview of existing operators and properties provided a uniform and complete picture, including many novel (even surprising) results on relations between properties and operators. Yet, this overview ignored to a large extent a different set properties for forgetting in ASP, and in this paper we close this gap. It turns out that, while some of these properties are closely related to the properties previously studied, four of them are distinct providing novel results and insights further strengthening established relations between existing operators.