In this paper, a possible worlds framework for representing general belief change operators is presented. In common with many approaches, an agent’s set of beliefs are specified by a subset of the set of possible worlds. The central intuition is that there is a distance given between every pair of possible worlds, giving the similarity of one world to another; the set of worlds together with th...

The semantics, or meaning, of validity is a fluid concept in educational and psychological testing. Contemporary controversies surrounding this concept appear to stem from the proper location of validity. Under one view, validity is a property of score-based inferences and entailed uses of test scores. This view is challenged by the instrument-based approach, which contends that tests themselve...

In this paper, we study the semantics for the logics of preference based on possibility theory. Possibility distributions representing the preference between worlds are associated with the possible world models for dynamic logics. Then the preference between actions are determined by comparing some measures of their consequences. We define different logics of preference by considering the compa...

We introduce Description Logics of Context (DLCs) — an extension of Description Logics (DLs) for context-based reasoning. Our approach descends from J. McCarthy’s tradition of treating contexts as formal objects over which one can quantify and express first-order properties. DLCs are founded in two-dimensional possible world semantics, where one dimension represents a usual object domain and th...

Here is a familiar history: modal logics (see [13]) were around for some time before a semantic framework was found for them (by Kripke and others).1 This framework did at least two Very Good Things for modal logics: 1) it connected the powerful mathematical tools of model theory to these logics, allowing a variety of technical results to be proven, and 2) it connected modal logics (more) firml...

The Logic of Approximate Entailment (LAE) is a graded counterpart of classical propositional calculus, where conclusions that are only approximately correct can be drawn. This is achieved by equipping the underlying set of possible worlds with a similarity relation. When using this logic in applications, however, a disadvantage must be accepted; namely, in LAE it is not possible to combine conc...

Possibilistic logic is an important framework for representing and reasoning with uncertain and inconsistent pieces of information. Standard possibilistic logic expressions are propositional logic formulas associated with positive real degrees belonging to [0,1]. Recently, a flexible representation of uncertain information, where the weights associated with formulas or possible worlds are in th...

David Lewis has long defended an analysis of counterfactuals in terms of comparative similarity of possible worlds.1 According to Lewis, a counterfactual of the form ̳If it were the case that A, then it would be that C‘ is (non-vacuously) true if and only if some world where A and C are both true is more similar to the actual world than any world where A is true and C is false. The purpose of th...

The Causal Theory of Properties (CTP) (Shoemaker, 1980a, 1980b, 1998) presents a striking picture: although a property might ultimately be distinct from the causal powers it confers on its instantiations (Shoemaker, 1998, p. 64), those causal powers limn the property’s identity. In the words of CTP’s leading proponent, Sydney Shoemaker, “The formulation of the causal theory of properties I now ...

In this paper, two families of merging operators are considered: quota operators and Gmin operators. Quota operators rely on a simple idea: any possible world is viewed as a model of the result of the merging when it satisfies “sufficiently many” bases from the given profile (a multi-set of bases). Different interpretations of the “sufficiently many” give rise to specific operators. Each Gmin o...