Modal Semantics for Knowledge Bases Dealing with Vague Concepts

The paper investigates the characterisation of vague concepts within the framework of modal logic. This work builds on the supervaluation approach of Fine and exploits the idea of a precisi cation space. A simple language is presented with two modalities: a necessity operator and an operator `it is unequivocal that' which is used to articulate the logic of vagueness. Both these operators obey the schemas of the logic S5. I show how this language can be used to represent logical properties of vague predicates which have a variety of possible precise interpretations. I consider the use within KR systems of number of di erent entailment relations that can be speci ed for this language. Certain vague predicates (such as `tall') may be inde nite even when there is no ambiguity in meaning. These can be accounted for by means of a three-valued logic, incorporating a definiteness operator. I also show the relationship between observable quantities (such as height) and vague predicat...

• Type: Conference
• Year: 1998
• Where: KR
• Authors: Brandon Bennett
• Keywords: Automated Reasoning, Certain Vague Predicates, KR 1998, Operator, Vague Predicates