People often mean more than they say. Grammar on its own is typically insufficient for determining the full meaning of an utterance; the assumption that the discourse is coherent or 'makes sense' has an important role to play in determining meaning as well. Logics of Conversation presents a dynamic semantic framework called Segmented Discourse Representation Theory, or SDRT, where this interaction between discourse coherence and discourse interpretation is explored in a logically precise manner. Combining ideas from dynamic semantics, commonsense reasoning (...) and speech act theory, SDRT uses its analysis of rhetorical relations to capture intuitively compelling implicatures. It provides a computable method for constructing these logical forms and is one of the most formally precise and linguistically grounded accounts of discourse interpretation currently available. The book will be of interest to researchers and students in linguistics and in philosophy of language. (shrink)

This paper presents a formal account of how to determine the discourse relations between propositions introduced in a text, and the relations between the events they describe. The distinct natural interpretations of texts with similar syntax are explained in terms of defeasible rules. These characterise the effects of causal knowledge and knowledge of language use on interpretation. Patterns of defeasible entailment that are supported by the logic in which the theory is expressed are shown to underly temporal interpretation.

This paper presents a novel account of focal stress and pitch contour in English dialogue. We argue that one should analyse and treat focus and pitch contour jointly, since (i) some pragmatic interpretations vary with contour (e.g., whether an utterance accepts or rejects; or whether it implicates a positive or negative answer); and (ii) there are utterances with identical prosodic focus that in the same context are infelicitous with one contour, but felicitous with another. We offer an account of two (...) distinct pitch contours that predicts the correct felicity judgements and implicatures, outclassing other models in empirical coverage or formality. Prosodic focus triggers a presupposition, where what is presupposed and how the presupposition is resolved depends on prosodic contour. If resolving the presupposition entails the proffered content, then the proffered content is uninteresting and hence the utterance is in-felicitous. Otherwise, resolving the presupposition may lead to an implicature. We regiment this account in SDRT. (shrink)

In this paper, we offer a novel analysis of presuppositions, paying particular attention to the interaction between the knowledge resources that are required to The analysis has two main features. First, we capture an analogy between presuppositions, anaphora and scope ambiguity (cf. van der Sandt 1992), by utilizing semantic under-specification (c£ Reyle 1993). Second, resolving this underspecification requires reasoning about how the presupposition is rhetorically connected to the discourse context. This has several consequences. First, since pragmatic information plays a role (...) in computing the rhetorical relation, it also constrains the interpretation of presuppositions. Our account therefore provides a formal framework for analysing problematic data, which require pragmatic reasoning. Second, binding presuppositions to the context via rhetorical links replaces accommodating them, in the sense of adding them to the context (cf. Lewis 1979). The treatment of presupposition is thus generalized and integrated into the discourse update procedure. We formalize this approach in SDRT (Asher 1993; Lascarides & Asher 1993), and demonstrate that it provides a rich framework for interpreting presuppositions, where semantic and pragmatic constraints are integrated. (shrink)

In this paper, we address several puzzles concerning speech acts, particularly indirect speech acts. We show how a formal semantictheory of discourse interpretation can be used to define speech acts and to avoid murky issues concerning the metaphysics of action. We provide a formally precise definition of indirect speech acts, including the subclass of so-called conventionalized indirect speech acts. This analysis draws heavily on parallels between phenomena at the speech act level and the lexical level. First, we argue that, just (...) as co-predication shows that some words can behave linguistically as if they're `simultaneously' of incompatible semantic types, certain speech acts behave this way too. Secondly, as Horn and Bayer (1984) and others have suggested, both the lexicon and speech acts are subject to a principle of blocking or "preemption by synonymy": Conventionalized indirect speech acts can block their `paraphrases' from being interpreted as indirect speech acts, even if this interpretation is calculable from Gricean-style principles. We provide a formal model of this blocking, and compare it with existing accounts of lexical blocking. (shrink)

In this paper, we address several puzzles concerning speech acts, particularly indirect speech acts. We show how a formal semantic theory of discourse interpretation can be used to define speech acts and to avoid murky issues concerning the metaphysics of action. We provide a formally precise definition of indirect speech acts, including the subclass of so-called conventionalized indirect speech acts. This analysis draws heavily on parallels between phenomena at the speech act level and the lexical level. First, we argue that, (...) just as co-predication shows that some words can behave linguistically as if they're 'simultaneously' of incompatible semantic types, certain speech acts behave this way too. Secondly, as Horn and Bayer and others have suggested, both the lexicon and speech acts are subject to a principle of blocking or "preemption by synonymy": Conventionalized indirect speech acts can block their 'paraphrases' from being interpreted as indirect speech acts, even if this interpretation is calculable from Gricean-style principles. We provide a formal model of this blocking, and compare it with existing accounts of lexical blocking. (shrink)

In this paper we explore how compositional semantics, discourse structure, and the cognitive states of participants all contribute to pragmatic constraints on answers to questions in dialogue. We synthesise formal semantic theories on questions and answers with techniques for discourse interpretation familiar from computational linguistics, and show how this provides richer constraints on responses in dialogue than either component can achieve alone.

In this paper, we offer a novel analysis of bridging, paying particular attention to definite descriptions. We argue that extant theories don't do justice to the way different knowledge resources interact. In line with Hobbs (1979), we claim that the rhetorical connections between the propositions introduced in the text play an important part. But our work is distinct from his in that we model how this source of information interacts with compositional and lexical semantics. We formalize bridging in a framework (...) known as SDRT (Asher 1993). We demonstrate that this provides a richer, more accurate interpretation of definite descriptions than has been offered so far. (shrink)

In this paper we investigate how discourse structure affects the meanings of words, and how the meanings of words affect discourse structure. We integrate three ingredients: a theory of discourse structure called SDRT, which represents discourse in terms of rhetorical relations that glue together the propositions introduced by the text segments; an accompanying theory of discourse attachment called DICE, which computes which rhetorical relations hold between the constituents, on the basis of the reader's background information; and a formal language for (...) specifying the lexical knowledge—both syntactic and semantic—called the LKB. Through this integration, we can model the information flow from words to discourse, and discourse to words. From words to discourse, we show how the LKE permits the rules for computing rhetorical relations in DICETO be generalized and simplified, so that a single law applies to several semantically related lexical items. From discourse to words, we encode two novel heuristics for lexical disambiguation: disambiguate words so that discourse incoherence is avoided, and disambiguate words so that rhetorical connections are reinforced. These heuristics enable us to tackle several cases of lexical disambiguation that have until now been outside the scope of theories of lexical processing. (shrink)

Humans face many game problems that are too large for the whole game tree to be used in their deliberations about action, and very little is understood about how they cope in such scenarios. However, when a human player’s chosen strategy is conditioned on her limited perspective of how the game might progress, then it should be possible to manipulate her into changing her planned move by mentioning a possible outcome of an alternative move. This paper demonstrates that human players (...) can be manipulated this way: in the game The Settlers of Catan, where negotiation is only a small part of what one must do to win the game thereby generating uncertainty about which outcomes to the negotiation are good and which are bad, the likelihood that a player accepts a trade offer that deviates from their declared preferred strategy is higher if it is accompanied by a description of what that trade offer can lead to. (shrink)

A semantic framework for interpreting dialogue should provide an account of the content that is mutually accepted by its participants. The acceptance by one agent of another’s contribution crucially involves the theory of what that contribution means; A’s acceptance of B’s contribution means that the content of B’s contribution must be integrated into A’s extant commitments.1 For assertions, traditionally assumed to express a proposition formalised as a set of possible worlds, it was clear how the integration should go: acceptance meant (...) intersecting the newly accepted proposition with the set of worlds representing the content of the agent’s prior commitments. Dynamic semantics (e.g., Asher (1989)) refined this picture by replacing intersection with the operation of dynamic update. The way to treat the negative counterpart of acceptance—namely, rejection—is also clear in principle: A s rejection of B’s assertion means that the negation of the content of B’s contribution should be integrated with the content of A’s prior commitments. However, acceptance and rejection don’t just happen with assertions. These speech acts can happen with questions as well. That is, an agent can choose to address the issues raised by the questioner; he can also choose to reject them. The explicit acceptance of a question can be conveyed by providing a direct answer or by an explicit admittance that one doesn’t know an answer; explicit rejection by uttering I won’t answer. (shrink)

Most models of rational action assume that all possible states and actions are pre-defined and that preferences change only when beliefs do. But several decision and game problems lack these features, calling for a dynamic model of preferences: preferences can change when unforeseen possibilities come to light or when there is no specifiable or measurable change in belief. We propose a formally precise dynamic model of preferences that extends an existing static model. Our axioms for updating preferences preserve consistency while (...) minimising change, like Hansson’s :1–28, 1995). But unlike prior models of preference change, ours supports default reasoning with partial preference information, which is essential to handle decision problems where the decision tree isn’t surveyable. We also show that our model avoids problems for other models of preference change discussed in Spohn. (shrink)

We present a formal analysis of iconic coverbal gesture. Our model describes the incomplete meaning of gesture that’s derivable from its form, and the pragmatic reasoning that yields a more specific interpretation. Our formalism builds reported.

’s glue logic for computing logical form dynamic. This allows us to model a dialogue agent’s understanding of what the update of the semantic representation of the dialogue would be after his next contribution, including the effects of the rhetorical moves that he is contemplating performing next. This is a pre-requisite for developing a model of how agents reason about what to say next. We make the glue logic dynamic by using a dynamic public announcement logic ( pal ). We (...) extend pal with a particular variety of default reasoning suited to reasoning about discourse—this default reasoning being an essential component of inferring the pragmatic effects of one’s dialogue moves. We add to the pal language a new type of announcement, known as ceteris paribus announcement, and this is used to model how an agent anticipates the (default) pragmatic effects of his next dialogue move. Our extended pal validates certain intuitive patterns of default inference that existing pal s for practical reasoning do not. We prove that the dynamic glue logic has a pspace validity problem, and as such is no more complex than pal with multiple $${\square}$$ operators. (shrink)

Several recent theories of linguistic representation treat the lexicon as a highly structured object, incorporating fairly detailed semantic information, and allowing multiple aspects of meaning to be represented in a single entry (e.g. Pustejovsky, 1991; Copestake, 1992; Copestake and Briscoe, 1995). One consequence of these approaches is that word senses cannot be thought of as discrete units which are in one-to-one correspondence with lexical entries. This has many advantages in allowing an account of systematic polysemy, but leaves the problem of (...) accounting for effects such as zeugma and the absence of crossed readings, which have traditionally been explained in terms of multiple lexical entries, but which can also arise in examples where other criteria demand that a single entry be involved. Copestake and Briscoe (1995) claimed that these cases could be explained by discourse coherence, but did not describe how this might work. We remedy this here, by formalising a general pragmatic principle which encapsulates discourse effects on word meaning. We demonstrate how it contributes to the creation of zeugma and the non-availability of crossed readings. (shrink)

In face-to-face interaction, speakers make multimodal contributions that exploit both the linguistic resources of spoken language and the visual and spatial affordances of gesture. In this paper, we argue that, in formulating and understanding such multimodal contributions, interlocutors apply the same principles of coherence that characterize the interpretation of natural language discourse. In particular, we use a close analysis of a series of naturally-occurring embodied discourses to argue for two key generalizations. First, communicators and their audiences draw on coherence relations (...) to establish interpretive connections between successive gestures and between gestures and speech. Second, coherence relations facilitate meaning-making by resolving the underspecified meaning of each communicative act through constrained inference over entities, propositions, and spatial frames made salient in the prior discourse. Our approach to gesture interpretation improves on previous work in better accounting for its flexibility, in capturing its constraints, and in laying the groundwork for formal and computational models. At the same time, it shows that gesture provides an important source of evidence to sharpen the theory of coherence relations and contextual resolution. (shrink)

We define an order independent version of default unification on typed feature structures. The operation is one where default information in a feature structure typed with a more specific type, will override default information in a feature structure typed with a more general type, where specificity is defined by the subtyping relation in the type hierarchy. The operation is also able to handle feature structures where reentrancies are default. We provide a formal semantics, prove order independence and demonstrate the utility (...) of this version of default unification in several linguistic applications. First, we show how it can be used to define multiple orthogonal default inheritance in the lexicon in a fully declarative fashion. Secondly, we show how default lexical specifications (introduced via default lexical inheritance) can be made to usefully persist beyond the lexicon and interact with syntagmatic rules. Finally, we outline how persistent default unification might underpin default feature propagation principles and a more restrictive and constraint-based approach to lexical rules. (shrink)

In this paper, we investigate the representation of negated sentences in Minimal Recursion Semantics (Copestake, Flickinger, Pollard, & Sag, 2005). We begin with its treatment in the English Resource Grammar (Flickinger, 2000, 2011), a broad-coverage implemented HPSG (Pollard & Sag, 1994), and argue that it is largely a suitable representation for English, despite possible objections. We then explore whether it is suitable for typologically different languages: namely, those that express sentential negation via inflection on the verb, particularly Turkish and Inuktitut. (...) We find that the interaction between negation and intersective modifiers requires a change to the way in which (at least) one of them contributes to semantic composition, and we argue for adapting the analysis of intersective modifiers. (shrink)

One way to construct semantic representations in a robust manner is to enhance shallow language processors with semantic components. Here, we provide a model theory for a semantic formalism that is designed for this, namely Robust Minimal Recursion Semantics (RMRS). We show that RMRS supports a notion of entailment that allows it to form the basis for comparing the semantic output of different parses of varying depth.

An essential part of natural language understanding, and hence of formal semantics, is the interpretation of temporal expressions. But the very variety of temporal phenomena---such as tense, aspect, aktionsart, temporal adverbials, and the temporal structure of extended text---has tended to result in formal semantic analyses using a wide variety of formal tools, often of a complex nature. It seems important to try and find unifying perspectives on this work, and above all, to try and gain some insight into the logical (...) resources needed to deal with natural language temporal phenomena. (shrink)

We propose a method for automatically identifying rhetorical relations. We use supervised machine learning but exploit cue phrases to automatically extract and label training data. Our models draw on a variety of linguistic cues to distinguish between the relations. We show that these feature-rich models outperform the previously suggested bigram models by more than 20%, at least for small training sets. Our approach is therefore better suited to deal with relations for which it is difficult to automatically label a lot (...) of training data because they are rarely signalled by unambiguous cue phrases (e.g., Continuation). (shrink)