Mark Steedman
Mark Steedman ( http://www.cogsci.ed.ac.uk/~steedman/) will be visiting here for 2 days, Feb. 22-23. He plans to arrive Wednesday evening and to leave with a late train Friday night. If you would like to meet with him, individually or in a team, please let Teresa know what times on Thursday and Friday would be good for you (and for how long you would like to meet). If at all possible, please do not request a unique hour, because it may not be compatible with other people's schedules. There's reason to believe that Mark will want to have lunch on both days, so some people might chat with him over lunch. He will also give two talks: 5pm on Thursday on "Surface-Compositional Semantics for Intonation" and 4:15 on Friday on "The Computational Problem of Language Acquisition". The second talk will to some extent build on the first.
Surface-Compositional Semantics for Intonation
Thursday Feb. 22, 5pm, Silver 805
This paper proposes a combined syntax and semantics for intonation in English. The semantics is surface-compositional under the generalized definition of surface-syntactic derivation afforded by Combinatory Categorial Grammar (CCG). This theory of grammar unites intonation structure and information structure with syntactic structure and Montague-style compositional semantics, even when intonation structure deviates from traditional surface structure. This semantics is based on four primitive dimensions of contrast, information structure, co-presence, and speaker/hearer supposition. Intonational effects described in the literature under headings like "turn-indication," "politeness," "continuation," "deixis," etc., arise indirectly from this semantics. he theory revises and extends earlier accounts of this kind, grounding semantic notions like ``theme'' and ``rheme'' (a.k.a. ``topic'' and ``comment,'' ``presupposition'' and ``focus,'' passim) in a logic of speaker/hearer supposition and update, and eliminating overgeneration in the CCG syntax. I will pay some attention to some well-known differences between English and the intonational system of Italian.
The Computational Problem of Natural Language Acquisition
Friday Feb. 23, 4:15pm, Silver 208
The paper reviews work-in-progress on language acquisition in children and robots using combinatory categorial grammar (CCG), building on work by Siskind, Villavicencio, and Zettlemoyer, among others.
CCG is a theory of grammar in which all language-specific grammatical information resides in the lexicon. A small universal set of strictly type-driven, non-structure dependent, syntactic rules (based on Curry's combinators B, S, and T) then "projects" lexical items into sentence-meaning pairs. The task that faces the child in the earliest stages of language acquisition can therefore be seen as learning a lexicon on the basis of exposure to (probably ambiguous, possibly somewhat noisy) sentence-meaning pairs, given this universal combinatory "projection principle", and a mapping from semantic types to the set of all universally available lexical syntactic types.
The paper argues that a very simple statistical model allows children to arrive at a target lexicon without navigation of subset principles, or attention to any attendant notion of trigger other than the notion "reasonably short sentence in a reasonably understandable situation". The model explains the pattern of errors that have been found in elicitation experiments. The linguistic notion of "parameter" appears to be redundant to this process.
The paper goes on to consider some more general implications of the theory, including its application to the phenomenon of "syntactic bootstrapping," touching on the question of the prelinguistic origin of the combinatory projection principle itself.
Last Modified: January 18, 2007