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Forgetting in Answer Set Programming – A Survey

Published online by Cambridge University Press:  27 December 2021

RICARDO GONÇALVES
Affiliation:
NOVA LINCS, Departamento de Informática, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal (e-mails: rjrg@fct.unl.ptrjrg@fct.unl.pt, mkn@fct.unl.ptmkn@fct.unl.pt, jleite@fct.unl.ptjleite@fct.unl.pt)
MATTHIAS KNORR
Affiliation:
NOVA LINCS, Departamento de Informática, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal (e-mails: rjrg@fct.unl.ptrjrg@fct.unl.pt, mkn@fct.unl.ptmkn@fct.unl.pt, jleite@fct.unl.ptjleite@fct.unl.pt)
JOÃO LEITE
Affiliation:
NOVA LINCS, Departamento de Informática, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal (e-mails: rjrg@fct.unl.ptrjrg@fct.unl.pt, mkn@fct.unl.ptmkn@fct.unl.pt, jleite@fct.unl.ptjleite@fct.unl.pt)
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Abstract

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Forgetting – or variable elimination – is an operation that allows the removal, from a knowledge base, of middle variables no longer deemed relevant. In recent years, many different approaches for forgetting in Answer Set Programming have been proposed, in the form of specific operators, or classes of such operators, commonly following different principles and obeying different properties. Each such approach was developed to address some particular view on forgetting, aimed at obeying a specific set of properties deemed desirable in such view, but a comprehensive and uniform overview of all the existing operators and properties is missing. In this article, we thoroughly examine existing properties and (classes of) operators for forgetting in Answer Set Programming, drawing a complete picture of the landscape of these classes of forgetting operators, which includes many novel results on relations between properties and operators, including considerations on concrete operators to compute results of forgetting and computational complexity. Our goal is to provide guidance to help users in choosing the operator most adequate for their application requirements.

Type
Original Article
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2021. Published by Cambridge University Press

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