We present a computationally eeective approach to representing and reasoning about actions with many qualiications. The approach involves treating actions as qualiied not by speciic facts that may or may not hold when the action is executed, but instead as potentially qualiied by general constraints describing the domain being investigated. Speciically, we suggest that the result of the action ...

We present a semantics for a language that includes sentences that can talk about their own probabilities. This semantics applies a fixed point construction to possible world style structures. One feature of the construction is that some sentences only have their probability given as a range of values. We develop a corresponding axiomatic theory and show by a canonical model construction that i...

Current literature offers a number of different approaches to what could generally be called “probabilistic logic programming”. These are usually based on Horn clauses. Here, we introduce a new formalism, Logic Programs with Annotated Disjunctions, based on disjunctive logic programs. In this formalism, each of the disjuncts in the head of a clause is annotated with a probability. Viewing such ...

In multi-agent systems, norms specify ideal behaviour. Agents, however, are autonomous, and may fail to comply with the ideal. Contrary to Duty obligations can be used to specify reparational behaviour that mitigates the effects of a violation. In addition to specifying reparational behaviours, it is important to understand how robust a system is against possible violations. Depending on what k...

Linguists often assume that possible worlds and times are represented as pronouns in natural language (see Cresswell 1990, Percus 2000, Kusumoto 2005, Keshet 2008). This paper will construe such pronouns as world-time pairs, which will be referred to as situations, for simplicity. A predicate taking such a pair as an argument is evaluated in the world and the time specified by that situation, e...

In his recent article, “Liability Rules When Injurers as Well as Victims Suffer Losses,“’ Avon Leong examines the question whether the standard liability rules-pure negligence, negligence with contributory negligence, pure strict liability and strict liability with contributory negligence-can be used to induce efficient care-taking by individuals in those circumstances where both injurers’ and ...

In this paper I will give a modal two-dimensional analysis of presupposition and modal subordination. I will think of presupposition as a non-veridical propositional attitude. This allows me to evaluate what is presupposed and what is asserted at different dimensions without getting into the binding problem. What is presupposed will be represented by an accessibility relation between possible w...

A distinction is drawn between situations as indices required for semantically evaluating sentences and situations as denotations resulting from such evaluation. For atomic sentences, possible worlds may serve as indices, and events as denotations. The distinction is extended beyond atomic sentences according to formulae-as-types and applied to implicit quantifier domain restrictions, intension...

We consider the issue of the sort of statements which a candidate running for office might make during the course of the campaign. We assume that there are various issues on which different groups of voters have preferences and that the candidate is aware of these different groups and their preferences. Her problem is to choose statements which will have the net effect of improving her percepti...

Estimating the cardinality (i.e., the number of answers) of conjunctive queries is particularly difficult in RDF systems: queries over RDF data are navigational and thus tend to involve many joins. We present a new, principled cardinality estimation technique based on graph summarisation. We interpret a summary of an RDF graph using a possible world semantics and formalise the estimation proble...