You Can't Always Forget What You Want

On the Limits of Forgetting in Answer Set Programming

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Citations (Scopus)

Abstract

Selectively forgetting information while preserving what matters the most is becoming an increasingly important issue in many areas, including in knowledge representation and reasoning. Depending on the application at hand, forgetting operators are defined to obey different sets of desirable properties. Of the myriad of desirable properties discussed in the context of forgetting in Answer Set Programming, strong persistence, which imposes certain conditions on the correspondence between the answer sets of the program pre- and post-forgetting, and a certain independence from non-forgotten atoms, seems to best capture its essence, and be desirable in general. However, it has remained an open problem whether it is always possible to forget a set of atoms from a program while obeying strong persistence. In this paper, after showing that it is not always possible to forget a set of atoms from a program while obeying this property, we move forward and precisely characterise what can and cannot be forgotten from a program, by presenting a necessary and sufficient criterion. This characterisation allows us to draw some important conclusions regarding the existence of forgetting operators for specific classes of logic programs, to characterise the class of forgetting operators that achieve the correct result whenever forgetting is possible, and investigate the related question of determining what we can forget from some specific logic program.
Original languageEnglish
Title of host publication22nd European Conference on Artificial Intelligence (ECAI 2016)
EditorsG. A. Kaminka, M. Fox, P. Bouquet, E. Hullermeier, V. Dignum, F. Dignum, F. VanHarmelen
Place of PublicationAmsterdam
PublisherIOS Press
Pages957-965
Number of pages9
ISBN (Electronic):978-1-61499-672-9
ISBN (Print)978-1-61499-671-2
DOIs
Publication statusPublished - 2016
Event22nd European Conference on Artificial Intelligence (ECAI 2016) - Hague, Netherlands
Duration: 29 Aug 20162 Sep 2016
Conference number: 22nd

Publication series

NameFrontiers in Artificial Intelligence and Applications
PublisherIOS Press
Volume285
ISSN (Print)0922-6389

Conference

Conference22nd European Conference on Artificial Intelligence (ECAI 2016)
Abbreviated titleECAI 2016
CountryNetherlands
CityHague
Period29/08/162/09/16

Keywords

  • LOGIC PROGRAMS
  • VARIABLE ELIMINATION
  • COMPLEXITY

Cite this

Goncalves, R., Knorr, M., & Leite, J. (2016). You Can't Always Forget What You Want: On the Limits of Forgetting in Answer Set Programming. In G. A. Kaminka, M. Fox, P. Bouquet, E. Hullermeier, V. Dignum, F. Dignum, & F. VanHarmelen (Eds.), 22nd European Conference on Artificial Intelligence (ECAI 2016) (pp. 957-965). (Frontiers in Artificial Intelligence and Applications; Vol. 285). Amsterdam: IOS Press. https://doi.org/10.3233/978-1-61499-672-9-957
Goncalves, Ricardo ; Knorr, Matthias ; Leite, Joao. / You Can't Always Forget What You Want : On the Limits of Forgetting in Answer Set Programming. 22nd European Conference on Artificial Intelligence (ECAI 2016). editor / G. A. Kaminka ; M. Fox ; P. Bouquet ; E. Hullermeier ; V. Dignum ; F. Dignum ; F. VanHarmelen. Amsterdam : IOS Press, 2016. pp. 957-965 (Frontiers in Artificial Intelligence and Applications).
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abstract = "Selectively forgetting information while preserving what matters the most is becoming an increasingly important issue in many areas, including in knowledge representation and reasoning. Depending on the application at hand, forgetting operators are defined to obey different sets of desirable properties. Of the myriad of desirable properties discussed in the context of forgetting in Answer Set Programming, strong persistence, which imposes certain conditions on the correspondence between the answer sets of the program pre- and post-forgetting, and a certain independence from non-forgotten atoms, seems to best capture its essence, and be desirable in general. However, it has remained an open problem whether it is always possible to forget a set of atoms from a program while obeying strong persistence. In this paper, after showing that it is not always possible to forget a set of atoms from a program while obeying this property, we move forward and precisely characterise what can and cannot be forgotten from a program, by presenting a necessary and sufficient criterion. This characterisation allows us to draw some important conclusions regarding the existence of forgetting operators for specific classes of logic programs, to characterise the class of forgetting operators that achieve the correct result whenever forgetting is possible, and investigate the related question of determining what we can forget from some specific logic program.",
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Goncalves, R, Knorr, M & Leite, J 2016, You Can't Always Forget What You Want: On the Limits of Forgetting in Answer Set Programming. in GA Kaminka, M Fox, P Bouquet, E Hullermeier, V Dignum, F Dignum & F VanHarmelen (eds), 22nd European Conference on Artificial Intelligence (ECAI 2016). Frontiers in Artificial Intelligence and Applications, vol. 285, IOS Press, Amsterdam, pp. 957-965, 22nd European Conference on Artificial Intelligence (ECAI 2016), Hague, Netherlands, 29/08/16. https://doi.org/10.3233/978-1-61499-672-9-957

You Can't Always Forget What You Want : On the Limits of Forgetting in Answer Set Programming. / Goncalves, Ricardo; Knorr, Matthias; Leite, Joao.

22nd European Conference on Artificial Intelligence (ECAI 2016). ed. / G. A. Kaminka; M. Fox; P. Bouquet; E. Hullermeier; V. Dignum; F. Dignum; F. VanHarmelen. Amsterdam : IOS Press, 2016. p. 957-965 (Frontiers in Artificial Intelligence and Applications; Vol. 285).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

TY - GEN

T1 - You Can't Always Forget What You Want

T2 - On the Limits of Forgetting in Answer Set Programming

AU - Goncalves, Ricardo

AU - Knorr, Matthias

AU - Leite, Joao

N1 - info:eu-repo/grantAgreement/FCT/5876/147279/PT# R. Gonçalves was partially supported by FCT grant SFRH/BPD/100906/2014 and M. Knorr by FCT grant SFRH/BPD/86970/2012.

PY - 2016

Y1 - 2016

N2 - Selectively forgetting information while preserving what matters the most is becoming an increasingly important issue in many areas, including in knowledge representation and reasoning. Depending on the application at hand, forgetting operators are defined to obey different sets of desirable properties. Of the myriad of desirable properties discussed in the context of forgetting in Answer Set Programming, strong persistence, which imposes certain conditions on the correspondence between the answer sets of the program pre- and post-forgetting, and a certain independence from non-forgotten atoms, seems to best capture its essence, and be desirable in general. However, it has remained an open problem whether it is always possible to forget a set of atoms from a program while obeying strong persistence. In this paper, after showing that it is not always possible to forget a set of atoms from a program while obeying this property, we move forward and precisely characterise what can and cannot be forgotten from a program, by presenting a necessary and sufficient criterion. This characterisation allows us to draw some important conclusions regarding the existence of forgetting operators for specific classes of logic programs, to characterise the class of forgetting operators that achieve the correct result whenever forgetting is possible, and investigate the related question of determining what we can forget from some specific logic program.

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KW - LOGIC PROGRAMS

KW - VARIABLE ELIMINATION

KW - COMPLEXITY

U2 - 10.3233/978-1-61499-672-9-957

DO - 10.3233/978-1-61499-672-9-957

M3 - Conference contribution

SN - 978-1-61499-671-2

T3 - Frontiers in Artificial Intelligence and Applications

SP - 957

EP - 965

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PB - IOS Press

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Goncalves R, Knorr M, Leite J. You Can't Always Forget What You Want: On the Limits of Forgetting in Answer Set Programming. In Kaminka GA, Fox M, Bouquet P, Hullermeier E, Dignum V, Dignum F, VanHarmelen F, editors, 22nd European Conference on Artificial Intelligence (ECAI 2016). Amsterdam: IOS Press. 2016. p. 957-965. (Frontiers in Artificial Intelligence and Applications). https://doi.org/10.3233/978-1-61499-672-9-957