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142
Modality in Dialogue: Planning, Pragmatics and Computation
, 1998
"... Natural language generation (NLG) is first and foremost a reasoning task. In this reasoning, a system plans a communicative act that will signal key facts about the domain to the hearer. In generating action descriptions, this reasoning draws on characterizations both of the causal properties of the ..."
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Cited by 36 (9 self)
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Natural language generation (NLG) is first and foremost a reasoning task. In this reasoning, a system plans a communicative act that will signal key facts about the domain to the hearer. In generating action descriptions, this reasoning draws on characterizations both of the causal properties of the domain and the states of knowledge of the participants in the conversation. This dissertation shows how such characterizations can be specified declaratively and accessed efficiently in NLG. The heart of this dissertation is a study of logical statements about knowledge and action in modal logic. By investigating the prooftheory of modal logic from a logic programming point of view, I show how many kinds of modal statements can be seen as straightforward instructions for computationally manageable search, just as Prolog clauses can. These modal statements provide sufficient expressive resources for an NLG system to represent the effects of actions in the world or to model an addressee whose knowledge in some respects exceeds and in other respects falls short of its own. To illustrate the use of such statements, I describe how the SPUD sentence planner exploits a modal knowledge base to
System Identification, Approximation and Complexity
 International Journal of General Systems
, 1977
"... This paper is concerned with establishing broadlybased systemtheoretic foundations and practical techniques for the problem of system identification that are rigorous, intuitively clear and conceptually powerful. A general formulation is first given in which two order relations are postulated on a ..."
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Cited by 34 (22 self)
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This paper is concerned with establishing broadlybased systemtheoretic foundations and practical techniques for the problem of system identification that are rigorous, intuitively clear and conceptually powerful. A general formulation is first given in which two order relations are postulated on a class of models: a constant one of complexity; and a variable one of approximation induced by an observed behaviour. An admissible model is such that any less complex model is a worse approximation. The general problem of identification is that of finding the admissible subspace of models induced by a given behaviour. It is proved under very general assumptions that, if deterministic models are required then nearly all behaviours require models of nearly maximum complexity. A general theory of approximation between models and behaviour is then developed based on subjective probability concepts and semantic information theory The role of structural constraints such as causality, locality, finite memory, etc., are then discussed as rules of the game. These concepts and results are applied to the specific problem or stochastic automaton, or grammar, inference. Computational results are given to demonstrate that the theory is complete and fully operational. Finally the formulation of identification proposed in this paper is analysed in terms of Klir’s epistemological hierarchy and both are discussed in terms of the rich philosophical literature on the acquisition of knowledge. 1
Modal Logic and Attribute Value Structures
 University of Amsterdam, ITLI
, 1993
"... This paper shows that there is a close correspondence between propositional modal logic and the AV formalisms of computational linguistics. A particularly important aspect of this relationship is that unification can be seen as testing for modal satisfiability. The paper considers three modal langua ..."
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Cited by 30 (8 self)
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This paper shows that there is a close correspondence between propositional modal logic and the AV formalisms of computational linguistics. A particularly important aspect of this relationship is that unification can be seen as testing for modal satisfiability. The paper considers three modal languages  L, L N and L KR  and for each of them describes the correspondence involved and proves results concerning completeness, decidability and expressive power. This paper examines the relationship between various languages of modal logic and an approach to the speci cation and processing of natural language grammars currently popular in computational linguistics. This approach is the use of Attribute Value formalisms, and the main aims of the paper are to show that the most common Attribute Value formalisms are nothing but languages of propositional modal logic, and to establish the basic logical theory of the languages concerned. The first section is an overview of the main ideas...
A Fixpoint Approach to SecondOrder Quantifier Elimination with Applications to Correspondence Theory
, 1995
"... This paper is about automated techniques for (modal logic) correspondence theory. The theory we deal with concerns the problem of finding fixpoint characterizations of modal axiom schemata. Given a modal schema and a semantics based method of translating modal formulae into classical ones, we try to ..."
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Cited by 28 (7 self)
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This paper is about automated techniques for (modal logic) correspondence theory. The theory we deal with concerns the problem of finding fixpoint characterizations of modal axiom schemata. Given a modal schema and a semantics based method of translating modal formulae into classical ones, we try to derive automatically a fixpoint formula characterizing precisely the class of frames validating this schema. The technique we consider can, in many cases, be easily applied without any computer support. Although we mainly concentrate on Kripke semantics, our fixpoint approach is much more general, as it is based on the elimination of secondorder quantifiers from formulae. Thus it can be applied in secondorder theorem proving as well. We show some application examples for the method which may serve as new, automated proofs of the respective correspondences.
The anaphoric parallel between modality and tense
, 1997
"... In modal subordination, a modal sentence is interpreted relative to a hypothetical scenario introduced in an earlier sentence. In this paper, I argue that this phenomenon reflects the fact that the interpretation of modals is an ANAPHORIC process, precisely analogous to the anaphoric interpretation ..."
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Cited by 24 (1 self)
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In modal subordination, a modal sentence is interpreted relative to a hypothetical scenario introduced in an earlier sentence. In this paper, I argue that this phenomenon reflects the fact that the interpretation of modals is an ANAPHORIC process, precisely analogous to the anaphoric interpretation of tense. Modal morphemes introduce alternative scenarios as entities into the discourse model; their interpretation depends on evoking scenarios for described, reference and speech points, and relating them to one another. Although this account formalizes anaphoric connections using dynamic semantics, it invokes a novel and direct encoding of scenarios as ordinary, static objects (competing analyses take modal referents to be inherently dynamic objects, unlike the referents of pronouns and tenses). The result is a simpler proposal with better empirical coverage.
The Logic of Correct Description
 Advances in Intensional Logic
, 1995
"... Austin's theory of truth is formulated in terms of a relation of correct description holding between a sentence and a situation. A recursive denition of correct description is provided for rstorder languages containing terms denoting situations and a predicate denoting correctdescription. We exam ..."
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Cited by 23 (1 self)
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Austin's theory of truth is formulated in terms of a relation of correct description holding between a sentence and a situation. A recursive denition of correct description is provided for rstorder languages containing terms denoting situations and a predicate denoting correctdescription. We examine a very strong logic of situations, by restricting our attention to situated consequence between descriptions of omniscient situations, arguing that weaker logics may be obtained using standard methods. Rules of natural deduction for the logic are introduced by way of examples of natural reasoning using spatial indexicals. Finally, a Gentzenstyle sequent calculus is oered. Keywords: Austin, truth, correct description, situation, indexical, natural deduction, sequent calculus. 1 Truth and Correct Description A basic tenet of situation semantics ([BP83, BE87, Bar89]), deriving from Austin's theory of truth ([Aus50]), is that every statement is about a situation. To make a statement by...
The Time Dimension in Conceptual Modelling
, 1991
"... In recent years there has been a growing interest in the explicit introduction of time modelling in a conceptual schema. This has come about as as a result of the relaisation that realisation that the development of large information systems is becoming increasingly more difficult as user requiremen ..."
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Cited by 21 (0 self)
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In recent years there has been a growing interest in the explicit introduction of time modelling in a conceptual schema. This has come about as as a result of the relaisation that realisation that the development of large information systems is becoming increasingly more difficult as user requirements become broader and more sophisticated. Arguably the most critical activity in the development of a large dataintensive information system is that of requirements capture and specification. The effectiveness of such a specification depends largely on the ability of the chosen conceptual model to represent the problem domain in such a way so as to permit natural and rigorous descriptions within a methodological framework. The explicit representation of time in a conceptual model plays a major role in achieving this effectiveness. This paper examines the ontology and properties of time in the context of information systems and conceptual modelling. In particular, a critical set of ontologic...
Modal proofs as distributed programs (Extended Abstract)
 EUROPEAN SYMPOSIUM ON PROGRAMMING
, 2004
"... We develop a new foundation for distributed programming languages by defining an intuitionistic, modal logic and then interpreting the modal proofs as distributed programs. More specifically, the proof terms for the various modalities have computational interpretations as remote procedure calls, c ..."
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Cited by 21 (0 self)
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We develop a new foundation for distributed programming languages by defining an intuitionistic, modal logic and then interpreting the modal proofs as distributed programs. More specifically, the proof terms for the various modalities have computational interpretations as remote procedure calls, commands to broadcast computations to all nodes in the network, commands to use portable code, and finally, commands to invoke computational agents that can find their own way to safe places in the network where they can execute. We prove some simple metatheoretic results about our logic as well as a safety theorem that demonstrates that the deductive rules act as a sound type system for a distributed programming language.
The power of the future perfect in program logics
 Information and Control
, 1985
"... The expressiveness of branching time tense (temporal) logics whose eventually operators are relativised to general paths into the future is investigated. These logics are interpreted in models obtained by generalising the usual notion of transition system to allow infinite transitions. It is shown t ..."
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Cited by 18 (0 self)
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The expressiveness of branching time tense (temporal) logics whose eventually operators are relativised to general paths into the future is investigated. These logics are interpreted in models obtained by generalising the usual notion of transition system to allow infinite transitions. It is shown that the presence of formulae expressing the future perfect enables one to prove that the expressiveness of the logic can be charaeterised by a notion of bisimulation on the generalised transition systems. The future perfect is obtained by adding a past tense operator to the language. Finally the power of various tense languages from the literature are