Antoine Venant’s research while affiliated with Université de Toulouse and other places

Our paper, ‘Message Exchange Games in Strategic Contexts’ lost the funding information and acknowledgments. We had put in it on its way to publication. We include them in this erratum here. © 2018 Springer Science+Business Media B.V., part of Springer Nature

When two people engage in a conversation, knowingly or unknowingly, they are playing a game. Players of such games have diverse objectives, or winning conditions: an applicant trying to convince her potential employer of her eligibility over that of a competitor, a prosecutor trying to convict a defendant, a politician trying to convince an electorate in a political debate, and so on. We argue that infinitary games offer a natural model for many structural characteristics of such conversations. We call such games message exchange games, and we compare them to existing game theoretic frameworks used in linguistics—for example, signaling games—and show that message exchange games are needed to handle non-cooperative conversation. In this paper, we concentrate on conversational games where players’ interests are opposed. We provide a taxonomy of conversations based on their winning conditions, and we investigate some essential features of winning conditions like consistency and what we call rhetorical cooperativity. We show that these features make our games decomposition sensitive, a property we define formally in the paper. We show that this property has far-reaching implications for the existence of winning strategies and their complexity. There is a class of winning conditions (decomposition invariant winning conditions) for which message exchange games are equivalent to Banach- Mazur games, which have been extensively studied and enjoy nice topological results. But decomposition sensitive goals are much more the norm and much more interesting linguistically and philosophically.

While a semantics without differing “points of view” of different agents is a good first hypothesis for the analysis of the content of monologue, dialogues typically involve differing points of view from different agents. In particular one agent may not agree with what another agent asserts, or may have a different interpretation of an utterance from that of its author. An adequate semantics for dialogue should proceed by attributing to different dialogue agents separate views of the contents of their conversation. We model this, following others, by assigning each agent her own commitment slate. In this paper we bring out a complication with this approach that has gone so far unnoticed in formal semantics and the prior work we just mentioned, albeit it is well-known from epistemic game theory: commitment slates interact; agents typically commit to the fact that other agents make certain commitments. We thus formulate the semantics of dialogue moves and conversational goals in terms of nested, public commitments. We develop two semantics for nested commitments, one for a simple propositional language, the other for a full description language for the discourse structure of dialogues; and we show how one is an approximation of the other. We apply this formal setting to provide a unified account of different linguistic problems: the problem of ambiguity and the problem of acknowledgments and grounding. We also briefly discuss the problem of corrections and how to integrate them in our framework.

This paper addresses the question of propositional attitude reports within segmented discourse representation theory (SDRT). In line with most SDRT discussions on attitudes reports, we argue that reported speech should be segmented as the rest of the discourse is, but we identify several issues raised by such a segmentation: first, the nature of some relations crossing the boundaries between main and embedded speech remains unclear. Moreover, such constructions are introducing a conflict between SDRT’s right frontier constraint (RFC) and well established facts about accessibility from factual to modal contexts. We propose two solutions for adapting discourse structure to overcome these conflicts. The first one introduces a new ingredient in the theory while the second one is more conservative and relies on continuation-style semantics for SDRT.

This paper investigates measures of semantic similarity between conversations from an axiomatic perspective. We abstract away from real conversations, representing them as sequences of formulas, equipped with a notion of semantic interpretation that maps them into a different space. An example we use to illustrate our approach is the language of propositional logic with its classical semantics. We introduce and study a range of different candidate properties for metrics on such conversations, for the structure of the semantic space, and for the behavior of the interpretation function, and their interactions. We define four different metrics and explore their properties in this setting.