Arbitrary public announcement logic ) reasons about how the knowledge of a set of agents changes after true public announcements and after arbitrary announcements of true epistemic formulas. We consider a variant of arbitrary public announcement logic called positive arbitrary public announcement logic ), which restricts arbitrary public announcements to announcement of positive formulas. Positive formulas prohibit statements about the ignorance of agents. The positive formulas correspond to the universal fragment in first-order logic. As two successive announcements of positive formulas (...) need not correspond to the announcement of a positive formula, \ is rather different from \. We show that \ is more expressive than public announcement logic \, and that \ is incomparable with \. We also provide a sound and complete infinitary axiomatisation. (shrink)

Tim French, Wiebe van der Hoek, Petar Iliev and Barteld Kooi. Succinctness of Epistemic Languages. In: T. Walsh (editor). Proceedings of the Twenty-Second International Joint Conference on Artificial Intelligence (IJCAI-11), pp. 881-886, AAAI Press, Menlo Park.

We examine various logics that combine knowledge, awareness, and change of awareness. An agent can become aware of propositional propositions but also of other agents or of herself. The dual operation to becoming aware, forgetting, can also be modelled. Our proposals are based on a novel notion of structural similarity that we call awareness bisimulation, the obvious notion of modal similarity for structures encoding knowledge and awareness.

In mining, manufacturing and industrial process industries, maintenance procedures are used as an aid to guide technicians through complex manual tasks. These procedures are not machine-readable, and cannot support reasoning in digitally integrated manufacturing systems. Procedure documents contain unstructured text and are stored in a variety of formats. The aim of this work is to query information held in real industrial maintenance procedures. To achieve this, we develop an ontology for maintenance procedures using the OWL 2 description language. We leverage (...) classes and object properties from the ISO 15926 Part 14 Upper Ontology and create a domain ontology. The key contribution of this paper is a demonstration of trade-offs required when modelling an existing engineering artifact, where an abstraction of its contents is given a-priori. We provide an ontologically rigorous abstraction of notions captured in procedure documentation to a set of classes, relations and axioms that allow reasoning over the contents. Validation of the ontology is performed via a series of competency questions based on queries relevant to technicians, engineers and schedulers in industry. The ontology is applied to real world maintenance procedures from two industrial organisations. (shrink)

We consider the relation between the uniform interpolation property and the elimination of non-standard quantifiers (the bisimulation quantifiers) in the context of the ?-calculus. In particular, we isolate classes of frames where the correspondence between these two properties is nicely smooth.

This paper compares the recently proposed Robust Full Computational Tree Logic to model robustness in concurrent systems with other computational tree logic -based logics. RoCTL* extends CTL* with the addition of the operators Obligatory and Robustly, which quantify over failure-free paths and paths with one more failure respectively. This paper focuses on examining the succinctness and expressiveness of RoCTL* by presenting translations to and from RoCTL*. The core result of this paper is to show that RoCTL* is expressively equivalent to (...) CTL* but is non-elementarily more succinct. That is, RoCTL* does not add any expressive power over CTL*, but can represent some properties using vastly reduced formulae. We present a translation from RoCTL* into CTL* that preserves truth but may result in non-elementary growth in the length of the translated formula, as each nested Robustly operator may result in an extra exponential blowup. However, we show that this translation is optimal in the sense th.. (shrink)