Quantify The Expansion Of The System Z And The Processing Of Discourse Representation Theory

The dissertation presents a simply treated sound and complete system for the first order fragment of Discourse Representation Theory. Since the inferences that human language users draw from the verbal input they receive for the most transcena the capacities of such a system, it can be no more than a basis on which more powerful systems, which are capable of producing those inferences, may then be built. Nevertheless, even within the general setting of first-order logic the structure of the "formulas" of DRS-language, i.e. of the Discourse Representation Structure suggest for the components of the first-order predicate calculus and which are more in keeping with inference patterns that are actually employed in common sense reasoning.Discourse Representation Theory (DRT) is a theory of semantics content of linguistic expressions - in particular, of natural language sentences, discourses and texts, as well as, more recently, of the content structure of thought. As a theory of the content of sentences and texts DRT has the following basic structure. Each text T consisting of sentences S\, ..., Sn determines a semantic representation K(T) (Such representations are called "Discourse Representation Structures', or "DRSs"). K(T) is constructed stepwise, by a procedure - the so-called "DRS-construction algorithm" - which processes the sentences S, one by one, in the order in which they occur in the text. The algorithm incorporates the content of Si into the DRS Ki-1, which it has already constructed for the sentences S1, ..., Si-1. The process of incorporating Si into Kj-1 makes use on the one hand of the syntactic structure of Si ancfon the other hand of the form of K\.\, and results in a new DRS which represents the integral content of the sentences. The process is designed to identify and encode the semantic connections between the successive sentences of a text - such as, for instance, those produced by pronouns whose anaphoric antecedents occur in earlier sentence - which are largely responsible for the cohesion that distinguishes genuine texts from mere successions of (unconnected) sentences. As a result, the final DRS K(T) of a text T represents the semantic contents of T as a whole, and does not just act as a compendium of the separate contents of the sentences S\, ...,Sn of which me text consists.According to what we have just said, DRSs emerge through application of the DRS- construction algorithm to texts belonging to the given natural language, and so the class of DRSs could be defined as consisting of just those structures which can be constructed in this way from an independently specified class of natural language inputs. It is also possible, however, to define the class of "well-formed" DRSs directly, in the manner familiar from mathematical logic. Such a definition presents DRSs as formulas belonging to some formal language - the "DRS language" - for which we can then specify a suitable semantics, logic ana proof theory. But how will we do with a simple treatment? The following is the perspective we will adopt.The system Z is a classical prepositional logic system with square bracket-notation which was constructed by Zhang Qingyu in 1997, in which the only connective is the generalized nor. Based on the system Z, we present a first-order predicate logic system ZL with square-notation like the system Z, in which the only connective is the generalized nor and the only quantifier is the existential quantifier. In semantics, there have no difference between the square-notation and square bracket-notation. In the formal language of the system ZL the square is used as bracket, and it is also viewecfas J_, semantically as falsehood, when nothing is in it. In the system ZL the square belongs to the formal language and meansnegation, but in DRT the square have no other meaning but only a sign in which the discourse references and the discourse conditions are bound. Thus we connect directly the DRS acted as the expression in the formal language of the system ZL and the DRS acted as semantic structu...