Online research in philosophy

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)

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.

In this paper we define agreement in terms of shared public commitments, and implicit agreement is conditioned on the semantics of the relational speech acts (e.g., Narration, Explanation) that each agent performs. We provide a consistent interpretation of disputes, and updating a logical form with the current utterance always involves extending it and not revising it, even if the current utterance denies earlier content.

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)

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)

In this paper, we offer a novel analysis of presuppositions, paying particular attention to the interaction between the knowledge resources that are required to interpret them. The analysis has two main features. First, we capture an analogy between presuppositions, anaphora and scope ambiguity (cf. van der Sandt, 1992), by utilising semantic underspecification (cf. 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 goes beyond existing ones, and provides a forum for analysing problematic data, that 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). Thus, unlike previous theories, we don't resort to interpretation mechanisms that are peculiar to presuppositions. Rather, they are handled entirely in terms of the discourse update procedure. We formalise this approach in SDRT (Asher 1993, Lascarides and Asher 1993), and demonstrate that it provides a rich framework for interpreting presuppositions, where semantic and pragmatic constraints are integrated. (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)

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)

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 actsand to avoid murky issues concerning the metaphysics of action. Weprovide a formally precise definition of indirect speech acts, includingthe subclass of so-called conventionalized indirect speech acts. Thisanalysis draws heavily on parallels between phenomena at the speechact level and the lexical level. First, we argue that, just as co-predicationshows 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 thelexicon and speech acts are subject to a principle of blocking or ``preemptionby synonymy'': Conventionalized indirect speech acts can block their`paraphrases' from being interpreted as indirect speech acts, even ifthis interpretation is calculable from Gricean-style principles. Weprovide a formal model of this blocking, and compare it withexisting 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.

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)

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)

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.