# Forgetting literals with varying propositional symbols

1 DREAM - Diagnosing, Recommending Actions and Modelling
Inria Rennes – Bretagne Atlantique , IRISA-D7 - GESTION DES DONNÉES ET DE LA CONNAISSANCE
Abstract : Recently, the old logical notion of forgetting propositional symbols (or reducing the logical vocabulary, called elimination of middle terms by Boole) has been generalized to a new notion: forgetting literals. The aim was to help the automatic computation of various formalisms which are currently used in knowledge representation. We extend here this notion, by allowing propositional symbols to vary while forgetting literals. We describe the new notion, on the syntactical and the semantical side We provide various different syntactical characterizations, in order to provide various methods for computing the notion introduced here. This confirms that one of the main interests of the notion of forgetting literals (original, and new version) is that it provides new kinds of methods of computation. Then, we show how to apply it to the computation of circumscription. This computation has been done before with standard literal forgetting, but here we show how introducing varying propositional symbols simplifies significantly the computation. We revisit a fifteen years old result about computing circumscription, showing that it can be improved in the same way. We provide hints in order to apply this forgetting method also to other logical formalisms.
Document type :
Journal articles
Domain :

https://hal.inria.fr/inria-00463004
Contributor : René Quiniou <>
Submitted on : Wednesday, March 10, 2010 - 6:08:13 PM
Last modification on : Friday, November 16, 2018 - 1:38:50 AM

### Identifiers

• HAL Id : inria-00463004, version 1

### Citation

Yves Moinard. Forgetting literals with varying propositional symbols. J. of Logic and Computation, Oxford University Press, 2007, 17 (5), pp.955--982. ⟨inria-00463004⟩

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