Declarative Update Policies for Nonmonotonic Knowledge Bases

Eiter, Thomas; Fink, Michael; Sabbatini, Giuliana; Tompits, Hans

doi:10.1007/978-3-642-18690-5_3

Cited by 2 publications

(12 citation statements)

References 17 publications

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“…, P n ) of ELPs as a representation, and aim at enforcing consistency of the knowledge base. For instance, in the dynamic logic programming semantics of sequences of ELPs [Alferes et al 2000;Eiter et al 2001], more recent rules occur later in a sequence and override rules from programs which occur earlier in the sequence; this mechanism is also used in the EPI framework for incorporating changes to the knowledge base at the logical level [Eiter et al , 2003.…”

Section: Evolution Framementioning

confidence: 99%

“…Observe that, while tr(·) as in Eiter et al [2001] is involved and has to keep track of persistent update commands always[ event](r) from the past, as shown by Eiter et al [2003], it is possible, by encoding persistent commands in polynomial time in the belief set, to restrict actions, without loss of expressiveness, to the commands assert and retract (whose meaning is the intuitive one) and making ρ actually depend only the belief set Bel(π n−1 (s)) of the predecessor and the event E n .…”

Section: Update Programs and Epimentioning

confidence: 99%

“…We remark that our general definition of evolution frames would permit to model extensions of EPI that feature temporal trigger events formulated in a language similar to the firstorder temporal logic with past temporal operators [Chomicki 1995] or to past temporal logic [Sistla and Wolfson 1995], and its impact on complexity remains to be analyzed. For further discussion of EPI, we refer to Eiter et al [2003].…”

Section: Update Programs and Epimentioning

confidence: 99%

“…Eiter et al [2003]). Furthermore, the policy EPI is sensible only to polynomially many rules in events, and comp EPI (s) contains only rules from a fixed set R 0 of rules, whose size is polynomial in the representation size of EF.…”

Section: Proof See Appendix B1mentioning

confidence: 99%

“…In this way, we identify meaningful conditions under which the problem ranges from PSPACE up to 2-EXPSPACE complexity. We then apply this to the EPI framework under the answer set semantics [Eiter et al , 2003, and show that its propositional fragment has PSPACE-complexity. Similar results may be derived for the LUPS and LUPS * frameworks.…”

Section: Introductionmentioning

confidence: 99%

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Reasoning about evolving nonmonotonic knowledge bases

Eiter

Fink

Sabbatini

et al. 2005

ACM Trans. Comput. Logic

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Recently, several approaches to updating knowledge bases modeled as extended logic programs have been introduced, ranging from basic methods to incorporate (sequences of) sets of rules into a logic program, to more elaborate methods which use an update policy for specifying how updates must be incorporated. In this article, we introduce a framework for reasoning about evolving knowledge bases, which are represented as extended logic programs and maintained by an update policy. We first describe a formal model which captures various update approaches, and we define a logical language for expressing properties of evolving knowledge bases. We then investigate semantical and computational properties of our framework, where we focus on properties of knowledge states with respect to the canonical reasoning task of whether a given formula holds in a given evolving knowledge base. In particular, we present finitary characterizations of the evolution for certain classes of framework instances, which can be exploited for obtaining decidability results. In more detail, we characterize the complexity of reasoning for some meaningful classes of evolving knowledge bases, ranging from polynomial to double exponential space complexity.

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Section: Evolution Framementioning

confidence: 99%

Section: Update Programs and Epimentioning

confidence: 99%