Mercer, R., 1987. A Default Logic Approach to the Derivation of Natural Language Presuppositions, PhD Dissertation, University of British Columbia.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....the presupposition itself is determined by context (e.g. 10) vs (11) 6 One could take an even more extreme position, and suggest that presuppositions are extra inferred knowledge, which strictly speaking doesn t comprise part of the semantic content of the text at all. As Gazdar (1979) and Mercer (1985) have argued, they are implicatures of some kind. We reject this extreme position. Treating presuppositions as part of the semantic content allows one to record how it affects the interpretation of other expressions in the text, such as pronouns (van der Sandt, 1992) 11 We capture the ....

Mercer, R. E. [1985] A Default Logic Approach to the Derivation of Natural Language Presuppositions, PhD dissertation, University of British Columbia.

....information is always cancelled by entailments or so that weaker defeasible information is always cancelled by stronger defeasible information. Although such a definition could account for the inferences that are most likely to be drawn from utterances of the kind shown in examples (5) 7) see Mercer (Mercer 1987) for an approach designed along these lines that handles presuppositions) it could not explain why defeating some pragmatic inferences is felicitous, while defeating others is not. It seems that logical systems that have been proposed for handling beliefs could not provide a direct explanation ....

Mercer, R. 1987. A Default Logic Approach to the Derivation of Natural Language Presuppositions.

....to improve on theories that have been presented in the philosophical and linguistic literature of discourse phenomena. Robert Mercer applied default logic to the theory of presupposition, and Jacques Wainer developed a circumscriptive theory of implicature phenomena. See [Mercer Reiter 1982] [Mercer 1987], Mercer 1988] and [Wainer 1991] 8.5. Mutual defaults Richmond Thomason has explored the use of mutual defaults (defaults about conversation that are mutually believed by the speaker and hearer in modeling ideas about conversation due to Robert Stalnaker and David Lewis. 90 These ....

Robert Mercer. A default logic approach to the derivation of natural language presuppositions. Doctoral Thesis, Department of Computer Science, University of British Columbia, 1987. Available as Technical Report TR 87-35, Department of Computer Science, University of British Columbia.

....is always cancelled by entailments or so that weaker defeasible information is always cancelled by stronger defeasible information. Although such a definition could account for the inferences that are most likely to be drawn from utterances of the kind shown in examples (5) 7) see Mercer [16] for an approach designed along these lines that handles presuppositions) it could not explain why defeating some pragmatic inferences is felicitous, while defeating others is not. In this paper, we argue that a possible way to account for both these facets of cancelability is to use the ....

R.E. Mercer, A Default Logic Approach to the Derivation of Natural Language Presuppositions, Ph.D. dissertation, Department of Computer Science, University of British Columbia, 1987.

....are defined in terms of plugs, holes, and filters [ Karttunen, 1973 ] consistency [ Gazdar, 1979 ] uncontroversiality [ Soames, 1982 ] or hypothetical and secondary contexts [ Kay, 1992 ] but nothing is said about the logical framework into which they may be expressed. An exception is Mercer s approach [ 1987 ] He abandons the projection method in favour of rules of inference in default logic. Our main objection is to Mercer s use of natural disjunction as an exclusive disjunction, and the reduction of natural implication to logical equivalence. Mercer [ 1993 ] argued that this is a consequence of ....

R.E. Mercer. A Default Logic Approach to the Derivation of Natural Language Presuppositions. PhD thesis, Department of Computer Science, University of British Columbia, 1987.

....components. However, there are several problems: no satisfactory account for the behaviour of disjunction is provided; the defeasibility of presuppositions is not addressed; and presupposition as an informative operation is only allowed as a repairing modification to the original framework. Mercer [12, 13] applies a default logic approach. This account originates from an approach to the projection problem that concentrates on how presupposition as an inference is defeated when inconsistent with more firmly established information (Gazdar [4, 5] Presuppositions (of negative sentences) are ....

Mercer, Robert Ernest, A Default Logic Approach to the Derivation of Natural Language Presuppositions,Technical Report 87-35, Department of Computer Science, University of British Columbia, Vancouver, B.C.,Canada.

....(presupposition in the case of Kempson and Burton Roberts) I shall instead start with a general logic designed to model a broad range of human reasoning and see how well it copes with the data of implicature and presupposition. In approaching the problem this way I take the same route as Mercer [Mer92a, Mer92b] who applies Reiter s default logic [Rei87] to presupposition, and Beaver [Bea93] who starts from considerations of anaphor and epistemic modality using a system of dynamic logic (see Groenendijk and Stokhof [GS91] and Veltman [Vel91] which he then applies to presupposition. I have settled on ....

....weakest links last. Gazdar s pragmatic theory of presupposition [Gaz79] also imposes an order on the application of inferences; however, he himself acknowledges this to be arbitrary and supported by no other reason than that it works. This aspect of his theory has been rightly criticized by Mercer [Mer92a] who offers a theory built in default logic that does away with ordering constraints. Like Gazdar s theory, this logic requires the ordering of inferences. However, in this case the ordering has a strong theory internal justification, based on the inferential strengths of the links, that is ....

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R.E. Mercer. A default logic approach to the derivation of natural language presuppositions. Technical Report 332, Department of Computer Science, The University of Western Ontario, 1992.

....there are by now a number of other theories which utilise Gazdar s approach of making presuppositions true by default. Mercer s cancellation account 28 See my [Bea95] and Burton Roberts review article, Bu89c] for discussion of problems with van der Sandt s definition of presupposition. [Me87, Me92] takes Gazdar s insight that presuppositions normally project, and are only canceled as a result of conflict with context or implicatures, and formalises that by explicitly encoding Gazdar s potential presuppositions as default inference rules within Reiter s Default Logic. Unlike Gazdar, Mercer ....

Mercer, R., 1987. A Default Logic Approach to the Derivation of Natural Language Presuppositions, PhD Dissertation, University of British Columbia.

....the diagnosis of children with learning disabilities. Default Logic 26 Goebel and Goodwin [Goebel and Goodwin, 1987] show how default logic can be used for planning and temporal prediction. They have considered how chronological minimization can be implemented in Theorist. In natural language, Mercer [Mercer, 1987; Mercer, 1990] and Csinger [Csinger and Poole, 1989] have considered how default logic can be used to formalise the problem of presupposition in natural language. Perrault [Perrault, 1987] has used default logic for a formalization of speech act theory. Van Arragon [van Arragon, 1990] uses nested ....

Robert Mercer. A default logic approach to the derivation of natural language presuppositions. Technical Report 35, University of British Columbia, October 1987.

....some of the potential presuppositions. The critics of his theory were mostly concerned with the ad hoc order in which the conversational context is enhanced, and the lack of grounds for this. However, they do not provide an insight into the logical properties that Gazdar s presupposition has. Mercer [ 1987 ] and Horton [ 1987 ] note that Gazdar s method does not allow presuppositions to be cancelled by knowledge added to the context by later utterances. This gives presuppositions a very interesting status, assigning them a dual life: they are cancellable in the first stage (the stage of their ....

....context. From our perspective, of maximal importance is the fact that Gazdar formalizes presuppositions, in positive environments, as logical implications [ Gazdar, 1979, p. 140 ] As we will show in section 1.3, this is a logical mistake. 1.2. 4 Mercer An orthogonal approach is taken by Mercer [ 1982, 1987, 1988b, 1988a, 1990, 1991 ] He abandons the projection method for rules of inference in default logic. Mercer uses Gazdar s formalization of Grice s cooperative principle, one of the basic pillars of all pragmatic approaches, and he provides a proof theoretic definition for presupposition in ....

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R.E. Mercer. A Default Logic Approach to the Derivation of Natural Language Presuppositions. PhD thesis, Department of Computer Science, University of British Columbia, 1987.

....would be crlterial) and since it is not so critical here to be so pedantic about the term presupposition, we will use this latter terminology. 228 . 2 Details of the Generation Method The study of the method using Default Logic as a replacement for the projection meth ods is the main theme of [Mercer, 1987]. A summary of this work appears in [Mercer, 1988b] An important contribution is the connection maple between presupposi tions and the context, in particular Gazdar s formalization of Grice s maxims. More precisely, default theories corresponding to a well defined set of cases which can be ....

.... derived from the hearer s knowledge base (KBx) and the utterance (represented as (u) to convey Gazdar s view of the Gricean maxims) generate the appropriate presuppositions for sentences such as those found in (2) and (3) The precise details for com puting the set of cases (which can be found in [Mercer, 1987, Mercer, 1988b] are not important for this paper. Instead, some examples will be provided in order that an understanding of how the Default Logic method generates the appropriate presuppositions for a variety of sentences. The default theories that correspond to the cases mentioned above will be ....

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R. E. Mercer. A Default Logic Approach to the Derivation of Natural Language Presuppositions. PhD thesis, Dept. of Computer Science, University of British Columbia, 1987.

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Mercer, R., 1987. A Default Logic Approach to the Derivation of Natural Language Presuppositions, PhD Dissertation, University of British Columbia.

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R.E. Mercer. A Default Logic Approach to the Derivation of Natural Language Presuppositions. PhD thesis, Department of Computer Science, University of British Columbia, 1987.

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R.E. Mercer. 1987. A Default Logic Approach to the Derivation of Natural Language Presuppositions. Ph.D. thesis, Department of Computer Science, University of British Columbia.

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