Computational and Logical Analysis of Pressuposition

众所周知，除了真值条件意义外，对话还会产生第二层意义，即预设，它源于对话中包含的句子。预设构成了句子被赋予真值的条件。例如，“太郎后悔自己学习了认知科学”这句话被赋予真值，只是因为它的前提是太郎学习了认知科学。不能总是假设预设是由对话中的先前句子明确表达的，因此，有必要根据先前的对话来计算预设意义。此外，预设以一种以上的方式实现，即投射。在本研究中：(1)为了将预设从之前的句子中分离出来，收集和分析了语言学数据。(2)基于这些数据，计算预设的推理过程被形式化。在满意度理论和回指消解的框架下进行形式化，并对该模型所做的预测进行了评估。(3)该投影模型已被嵌入到计算机自然语言处理系统中，作为其上下文分析器的一部分。

It is well known that, in addition to truth-conditional meanings, dialogues give rise to secondary meaning known as presupposition which is derived from sentences contained in the dialogue. Presuppositions constitute a condition for a sentence to be assigned a truth value. For example, the sentence, "Taro regrets that he has studied cognitive science," is assigned a truth-value only because it presupposes that Taro has studied cognitive science. It cannot be always assumed that presuppositions are explicitly expressed by previous sentences in the dialogue, and therefore, it is necessary to calculate presupposed meanings based upon the preceding dialogue. Furthermore, presuppositions are realized, i.e. projected, in more than one way. In this research :(1)To isolate the way presuppositions are projected from preceding sentences, linguistic data have been collected and analyzed.(2)Based upon the data, the inference process to calculate the projected presuppositions has been formalized. The formalization is cast in the framework of Satisfaction Theory and Anaphoric Resolution, and the predictions made by the model has been evaluated.(3)The projection model has been embedded in a computer system for natural language processing, as part of its context analyzer.