A Random Set and Prototype Theory Model of Linguistic Query Evaluation

A Random Set and Prototype Theory Model of Linguistic Query Evaluation

Jonathan Lawry (University of Bristol, UK) and Yongchuan Tang (Zhejiang University, PR China)
DOI: 10.4018/978-1-60566-858-1.ch006
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Abstract

This chapter proposes a new interpretation of quantified linguistic queries based on a combination of random set theory and prototype theory and which is consistent with the label semantics framework. In this approach concepts are defined by random set neighbourhoods of a set of prototypes and quantifiers are similarly defined by random set constraints on ratios or absolute values. The authors then propose a computationally feasible method for evaluating quantified statement describing the elements of a database.
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Label Semantics

In contrast to fuzzy set theory, label semantics encodes the meaning of linguistic labels according to how they are used by a population of communicating agents to convey information. From this perspective, the focus is on the decision making process an intelligent agent must go through in order to identify which labels or expressions can actually be used to describe an object or value. In other words, in order to make an assertion describing an object in terms of some set of linguistic labels, an agent must first identify which of these labels are appropriate or assertible in this context. Given the way that individuals learn language through an ongoing process of interaction with the other communicating agents and with the environment, then we can expect there to be considerable uncertainty associated with any decisions of this kind. Furthermore, there is a subtle assumption central to the label semantic model, that such decisions regarding appropriateness or assertibility are meaningful. For instance, the fuzzy logic view is that vague descriptions like ‘John is tall' are generally only partially true and hence it is not meaningful to consider which of a set of given labels can truthfully be used to described John's height. However, we contest that the efficacy of natural language as a means of conveying information between members of a population lies in shared conventions governing the appropriate use of words which are, at least loosely, adhere to by individuals within the population.

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