Verification of Context-Sensitive Knowledge and Action Bases

Abstract

Abstract. Knowledge and Action Bases (KABs) have been recently proposed as a formal framework to capture the dynamics of systems which manipulate Description Logic (DL) Knowledge Bases (KBs) through action execution. In this work, we enrich the KAB setting with contextual information, making use of different context dimensions. On the one hand, context is determined by the environment using context-changing actions that make use of the current state of the KB and the current context. On the other hand, it affects the set of TBox assertions that are relevant at each time point, and that have to be considered when processing queries posed over the KAB. Here we extend to our enriched setting the results on verification of rich temporal properties expressed in μ-calculus, which had been established for standard KABs. Specifically, we show that under a run-boundedness condition, verification stays decidable and does not incur in any additional cost in terms of worst-case complexity. We also show how to adapt syntactic conditions ensuring run-boundedness so as to account for contextual information, taking into account context-dependent activation of TBox assertions.

Verification of Semantically-Enhanced Artifact Systems

“…For a detailed semantics of μL EQL A , refer to [2,11]. Given a SAS S, we show that verification of μL …”

“…As verification formalism, we consider a variant of first-order μ-calculus [15,22], called μL EQL A [2,11]. We observe that μ-calculus is one of the most powerful temporal logics: it subsumes LTL, PSL, and CTL* [12].…”

Verification of Semantically-Enhanced Artifact Systems (Extended Version)

“…Given a SAS S, we are interested in studying verification of semantic dynamic/temporal properties specified over the Semantic Layer, i.e., to be checked against the STS Υ S S . As verification formalism, we consider a variant of first-order µ-calculus [16,25], called µL EQL A [2,11]. We observe that µ-calculus is one of the most powerful temporal logics: it subsumes LTL, PSL, and CTL* [12].…”

“…Where Q is an ECQ over T , Z is a second-order variable denoting a 0-ary predicate, µ is the least fixpoint operator, and the special predicate LIVE(x) is used to indicate that x belongs to the current active domain, i.e., it is mentioned in some concept or role of the current ABox. For a detailed semantics of µL EQL A , refer to [2,11]. Given a SAS S, we show that verification of µL EQL A properties over the STS Υ S S can be reduced to verification of µL A [10] properties over the RTS Υ R S , where µL A is a logic similar to µL EQL A , except for the local formula Q, which is an (open) first-order query over the database schema in the Relational Layer.…”

Reasoning about actions with Temporal Answer Sets

“…In [8] Description Logic and Action Bases are introduced, where an initial Abox evolves over time due to actions which have conditional effects. In [11] the approach is extended to allow for different notions of repairing of the resulting state, such as a maximal subset consistent with the Tbox, or the intersection of all such subsets. In this paper, we rely on causal laws for repairing states; selecting the appropriate causal laws means acquiring more knowledge, and allows for a finer control on the resulting state.…”