9:15-9:30 h. Opening remarks
Human language defines the most complex outcomes of evolution. The emergence of such an elaborated form of communication allowed humans to create extremely structured societies and manage symbols at diferent levels including, among others, semantics. All linguistic levels have to deal with an astronomic combinatorial potential that stems from the recursive nature of languages. This recursiveness is indeed a key defining trait. However, not all words are equally combined nor frequent. In breaking the symmetry between less and more often used and between less and more meaning-bearing units, universal scaling laws arise. Such laws, common to all human languages, appear on diferent scales from word inventories to networks of interacting words. Among the seemingly universal traits exhibited by language networks, ambiguity appears to be a specially relevant component. Ambiguity is avoided in most computational approaches to language processing, and yet it seems to be a crucial element of language architecture. In our talk we will review the evidence both from language network architecture and from theoretical reasonings based on a least effort argument. Ambiguity is shown to play an essential role in providing a source of language efficiency, and is likely to be an inevitable byproduct of network growth.
The paper argues that syntax is motivated by the need to avoid combinatorial search in parsing and semantic ambiguity in interpretation. It reports on case studies for the emergence and sharing of constituent structures in a population of agents playing language games. To study why human languages exhibit constituent structure, a series of strategies for creating and sharing linguistic conventions are examined, starting from a lexical strategy without syntax and then studying the use of groups, n-grams, patterns and finally full blown hierarchical and recursive constituent structure. Each time we show in which way a strategy improves on the computational complexity of the previous on.
11:30-12:00 h. Coffee break
We will present the main results obtained in Fortuny & Corominas-Murtra (2013) and we will raise certain further questions relative to the study of the information-theoretical requirements that natural communication systems must satisfy. We will argue against the intuition that the presence of ambiguity in natural languages suggests that language is poorly designed for communication. We observe that if we take into consideration the complexities of both coding and decoding processes and we assume that communicative agents tend to minimize these two processes, then a certain amount of ambiguity must emerge. We express this tendency in terms of a symmetry equation between the coding and the decoding complexities that allows us to quantify the minimal amount of ambiguity that must appear. Furthermore, following Corominas-Murtra, Fortuny & Solé (2014), we will show that additional looses of information must be taken into account in natural communication when no designer is at work due to the non-guaranteed conservation of referentiality in autonomous systems.
J. Fortuny & B. Corominas-Murtra. 2013. On the Origin of Ambiguity in Efficient Communication. Journal of Logic, Language and Information (doi:10.1007/s10849-013-9179-3).
B. Corominas-Murtra, J. Fortuny & R. Solé. Towards a mathematical thory of meaningful communication. e-print: http://http://arxiv.org/abs/1004.1999
Categorial derivations map homomorphically to intuitionistic proofs, which constitute a programming language representing and composing the meanings of words and expressions. When there is (structural) *ambiguity* two different categorial derivations over the same categorial types map to *non-equal* intuitionistic programs. A notorious problem is *spurious ambiguity*, whereby two categorial derivations over the same categorial types map to *equal* intuitionistic programs. In this paper we discuss Girard's proof nets as the eventual solution to spurious ambiguity, and Andreoli's focalization as a stepping stone towards this solution.
Much recent work in formal pragmatics has focused on how pragmatic reasoning helps to resolve semantic ambiguity and underspecification. Standard examples are scalar implicatures and Horn's division of pragmatic labor. In these cases, the pragmatically conveyed interpretation is more specific than the literal meaning.
Game theoretic pragmatics correctly predicts these patterns. However, it also covers cases where pragmatic reasoning leads to a weakening of the literal meaning. In combination with context dependence, this creates the effect of pragmaticall ambiguiating expressions that are per se unambiguous. A typical case in point is the precise/vague ambiguity of measure terms observed by Krifka.
Natural languages come in two different modalities – the auditory-oral modality of spoken languages and the visual-manual modality of sign languages. The impact of modality on the grammatical system has been discussed at great length in the last 20 years. By contrast, the impact of modality on semantics in general and on ambiguities in particular has not yet been addressed in detail. In this talk, we deal with different types of ambiguities in sign languages. We discuss typical lexical and structural ambiguities as well as modality-specific aspects such as ambiguities in the use of the signing space and non-manual markers. In addition, we address the questions how sign languages avoid ambiguities and to what extent certain kinds of ambiguities and non-ambiguities depend on the visual-manual modality of sign languages. Since gestures use the same articulatory channel that is also active in the production of signs, we also discuss ambiguities between gestures on the one hand and grammaticalized gestures and signs on the other.
In this communication we focus on the topic of ambiguity resolution in/beyond grammar. We deal with two topics: where is ambiguity resolved (in particular, the ambiguity of expressions conveying specific forms of information packaging and common ground management), and what is the design of grammar that emerges from the study of ambiguity problems. After a review of the standard analysis of ambiguity within the Principles and Parameters model, in which ambiguous syntactic objects require different structures at syntax, we will focus on various phenomena that will support a model of grammar in which syntactic structures are mapped into information structures, which will feed both logical form and PF interfaces. In particular, we will show that scope relations between numeral quantifiers in Catalan and the interpretation of preverbal bare nominals in Brazilian Portuguese are sensitive to information structures that are to be translated into representations of meaning different from classical LFs. Only PFs are ambiguous.
11:30-12:00 h. Coffee break
In this paper we investigate the role of prosody and gesture in the interpretation of yes-answers to negative yes/no-questions in Catalan, a language with a polarity-based system of confirmation/contradiction of negative yes/no-questions. Two rating experiments were conducted to test (i) whether yes-answers to negative yes/no-questions are perceived as ambiguous by Catalan speakers when prosody and gesture are not available (Experiment 1), and (ii) whether the interpretation of sí ‘yes’ as an answer to a negative yes/no-question is dependent on prosodic and gestural properties of the answer (Experiment 2). Our results show that yes always asserts a salient propositional discourse referent, which can be either p or ¬p. Intonation and gesture guide the interpretation of yes-answers to negative yes/no-questions in Catalan, and we show that a yes-answer with a marked intonation and gesture is to be interpreted as a denial or REJECT of a salient propositional discourse referent.
Recently, a number of theories have been proposed to explain the use of polarity particles like yes and no (cf. Kramer & Rawlins 2009, Holmberg 2012, Farkas & Roelofsen 2012) that effectively posit that they are ambiguous. For example, we can react to the assertion John isn't coming to the party with either No, he isn't or No, he is. I propose an analysis of polarity particles as anaphoric expressions that pick up propositional discourse referents introduced by the antecedent clause, and argue that the ambiguity lies in the fact that negated antecedent clauses introduce two propositional antecedent clauses, one the negation of the other. It will be shown that pragmatic optimization leads to the selection of favorite answers in systems like English (with yes and no) and German (with ja, nein and doch).
16:00 h. Closing remarks