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Steps Toward Formalizing Context
 AI Magazine
, 1996
"... I wish honorable gentlemen would have the fairness to give the entire context of what I did say, and not pick out detached words. (Cobden, Speeches 46, 1849, quoted intheOED) The importance of contextual reasoning is emphasized by various researchers in AI. ..."
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Cited by 70 (5 self)
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I wish honorable gentlemen would have the fairness to give the entire context of what I did say, and not pick out detached words. (Cobden, Speeches 46, 1849, quoted intheOED) The importance of contextual reasoning is emphasized by various researchers in AI.
Tense and the logic of change
 Lexical Knowledge in the Organization of Language
, 1995
"... There are three major currents in semantic theory these days. First there is what Chierchia [1990] aptly calls “what is alive of classical Montague semantics”. Secondly, there is Discourse Representation Theory. Thirdly, there is ..."
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Cited by 65 (7 self)
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There are three major currents in semantic theory these days. First there is what Chierchia [1990] aptly calls “what is alive of classical Montague semantics”. Secondly, there is Discourse Representation Theory. Thirdly, there is
On the Foundations of Final Semantics: NonStandard Sets, Metric Spaces, Partial Orders
 PROCEEDINGS OF THE REX WORKSHOP ON SEMANTICS: FOUNDATIONS AND APPLICATIONS, VOLUME 666 OF LECTURE NOTES IN COMPUTER SCIENCE
, 1998
"... Canonical solutions of domain equations are shown to be final coalgebras, not only in a category of nonstandard sets (as already known), but also in categories of metric spaces and partial orders. Coalgebras are simple categorical structures generalizing the notion of postfixed point. They are ..."
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Cited by 47 (10 self)
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Canonical solutions of domain equations are shown to be final coalgebras, not only in a category of nonstandard sets (as already known), but also in categories of metric spaces and partial orders. Coalgebras are simple categorical structures generalizing the notion of postfixed point. They are also used here for giving a new comprehensive presentation of the (still) nonstandard theory of nonwellfounded sets (as nonstandard sets are usually called). This paper is meant to provide a basis to a more general project aiming at a full exploitation of the finality of the domains in the semantics of programming languages  concurrent ones among them. Such a final semantics enjoys uniformity and generality. For instance, semantic observational equivalences like bisimulation can be derived as instances of a single `coalgebraic' definition (introduced elsewhere), which is parametric of the functor appearing in the domain equation. Some properties of this general form of equivalence are also studied in this paper.
Recursive Subtyping Revealed
 Journal of Functional Programming
, 2000
"... Algorithms for checking subtyping between recursive types lie at the core of many programming language implementations. But the fundamental theory of these algorithms and how they relate to simpler declarative specifications is not widely understood, due in part to the difficulty of the available in ..."
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Cited by 37 (4 self)
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Algorithms for checking subtyping between recursive types lie at the core of many programming language implementations. But the fundamental theory of these algorithms and how they relate to simpler declarative specifications is not widely understood, due in part to the difficulty of the available introductions to the area. This tutorial paper offers an "endtoend" introduction to recursive types and subtyping algorithms, from basic theory to efficient implementation, set in the unifying mathematical framework of coinduction. 1. INTRODUCTION Recursively defined types in programming languages and lambdacalculi come in two distinct varieties. Consider, for example, the type X described by the equation X = Nat!(Nat\ThetaX): An element of X is a function that maps a number to a pair consisting of a number and a function of the same form. This type is often written more concisely as X.Nat!(Nat\ThetaX). A variety of familiar recursive types such as lists and trees can be defined analogou...
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
Situativity and symbols: Response to vera and simon
 Cognitive Science
, 1993
"... Vera and Simon (1993) have provided a helpful and welcome challenge in their articulate questioning of the point of view that emphasizes the situated character of action, including cognition and learning. A full discussion of their arguments and examples requires more space than we are allotted for ..."
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Cited by 30 (1 self)
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Vera and Simon (1993) have provided a helpful and welcome challenge in their articulate questioning of the point of view that emphasizes the situated character of action, including cognition and learning. A full discussion of their arguments and examples requires more space than we are allotted for this response, and we are preparing a longer article that will consider the issues they raised in more detail. We also welcome this opportunity to comment briefly on their provocative arguments. The Issue of Symbols Vera and Simon attribute several beliefs to researchers who are developing situativity theory, some of which we disclaim for ourselves and consider dubious regarding other situativity theorists. However, we do accept their characterization that our view "denies that symbolic processing lies at the heart of intelligence " (pp. 78). As we understand the current state of the debate, the issue hinges crucially on the meaning and theoretical status of the concept of symbol. In our view, the emerging scientific practices, empirical findings, and theory that we call Situativity theory; include the development of ecological
Situations: A general framework for studying Information Retrieval
, 1994
"... This paper presents a framework for the theoretical comparison of information retrieval models based on how the models decide aboutness. The framework is based on concepts emerging from the eld of situation theory. So called infons and profons represent elementary information carriers which can be m ..."
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Cited by 26 (17 self)
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This paper presents a framework for the theoretical comparison of information retrieval models based on how the models decide aboutness. The framework is based on concepts emerging from the eld of situation theory. So called infons and profons represent elementary information carriers which can be manipulated by union and fusion operators. These operators allow relationships between information carriers to be established. Sets of infons form so called situations which are used to model the information born by objects such as documents. An arbitrary information retrieval model can be mapped down into the framework. Special functions are de ned for this purpose depending on the model at hand. An important aspect is the inference mechanism which is mapped to inference between situations. Two examples are given based on the Boolean retrieval and coordination level matching models. The framework allows the comparison of retrieval models at an abstract level. Starting from an axiomatization of aboutness, retrieval models can be compared according to which axioms they are governed by. This approach is highlighted by the theoretical comparison of Boolean retrieval with coordinate level matching. This work was partly performed while employed at the Utrecht University. 1 1
The power of paradox: some recent developments in interactive epistemology
 International Journal of Game Theory
, 2007
"... Abstract Paradoxes of gametheoretic reasoning have played an important role in spurring developments in interactive epistemology, the area in game theory that studies the role of the players ’ beliefs, knowledge, etc. This paper describes two such paradoxes – one concerning backward induction, the ..."
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Cited by 26 (2 self)
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Abstract Paradoxes of gametheoretic reasoning have played an important role in spurring developments in interactive epistemology, the area in game theory that studies the role of the players ’ beliefs, knowledge, etc. This paper describes two such paradoxes – one concerning backward induction, the other iterated weak dominance. We start with the basic epistemic condition of “rationality and common belief of rationality ” in a game, describe various ‘refinements ’ of this condition that have been proposed, and explain how these refinements resolve the two paradoxes. We will see that a unified epistemic picture of game theory emerges. We end with some new foundational questions uncovered by the epistemic program. 1
On the Origins of Bisimulation and Coinduction
"... The origins of bisimulation and bisimilarity are examined, in the three fields where they have been ..."
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Cited by 25 (0 self)
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The origins of bisimulation and bisimilarity are examined, in the three fields where they have been
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...