Tim FRENCH

Aleatoric propositions are a generalisation of Boolean propositions, that are intrinsically probabilistic, or determined by the toss of a (biased) coin. Rather than let propositions take a true/false valuation, we assume they act as a biased coin, that will sometimes land heads (true), and sometimes land tails (false). Complex propositions then correspond to a conditional series of tosses of these coins. We extend the syntax and semantics for Aleatoric Logic to include a novel fixed-point operator that is able to represent a weak form of iteration. We examine the expressivity of the of the language, showing a correspondence to classes of rational functions over (0, 1)

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.

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.

This paper demonstrates the undecidability of a number of logics with quantification over public announcements: arbitrary public announcement logic, group announcement logic, and coalition announcement logic. In APAL we consider the informative consequences of any announcement, in GAL we consider the informative consequences of a group of agents all of which are simultaneously making known announcements. So this is more restrictive than APAL. Finally, CAL is as GAL except that we now quantify over anything the agents not in that group may announce simultaneously as well. The logic CAL therefore has some features of game logic and of ATL. We show that when there are multiple agents in the language, the satisfiability problem is undecidable for APAL, GAL, and CAL. In the single agent case, the satisfiability problem is decidable for all three logics.

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..