A bird’s-eye view of forgetting in answer-set programming

Forgetting is an operation that allows the removal, from a knowledge base, of middle variables no longer deemed relevant, while preserving all relationships (direct and indirect) between the remaining variables. When investigated in the context of Answer-Set Programming, many different approaches to forgetting have been proposed, following different intuitions, and obeying different sets of properties. This talk will present a bird’s-eye view of the complex landscape composed of the properties and operators of forgetting defined over the years in the context of Answer-Set Programming, zooming in on recent findings triggered by the formulation of the so-called strong persistence, a property based on the strong equivalence between an answer-set program and the result of forgetting modulo the forgotten atoms, which seems to best encode the requirements of the forgetting operation.