Seminar: Stephen Clark

In this talk I will describe a mathematical framework for a unification of the distributional theory of meaning in terms of vector space models, and a compositional theory for grammatical types. The syntactic part of the model assumes a type-driven syntax based on Categorial Grammar. The compositional framework enables us to compute the distributional meaning of a well-typed sentence from the distributional meanings of its constituents. Importantly, meanings of whole sentences live in a single space, independent of the grammatical structure of the sentence. Hence the inner-product can be used to compare meanings of arbitrary sentences, as it is for comparing the meanings of words in the distributional model.

 One way to consider this framework is that it takes the type-driven semantic composition process from the familiar Montague semantics and applies it to vector-space models of lexical semantics.

 An important question when applying the framework is what the type of the sentence space should be. I will describe some recent work in which we manually define such a sentence type, based on linguistic intuition, and also describe some recent experimental work in which the framework is evaluated. Joint work with Bob Coecke, Ed Grefenstette and Mehrnoosh Sadrzadeh

References

"Mathematical Foundations for a Compositional Distributional Model of Meaning" Bob Coecke, Mehrnoosh Sadrzadeh, and Stephen Clark

Linguistic Analysis, 36(1-4): A Festschrift for Joachim Lambek, pp. 345-384, van Bentham and Moortgat (eds), 2011

 E. Grefenstette and M. Sadrzadeh, "Experimental Support for a Categorical Compositional Distributional Model of Meaning,"

Proceedings of the 2011 Conference on Empirical Methods in Natural Language Processing, 2011.

Bio: Stephen Clark is a Senior Lecturer at the University of Cambridge Computer Laboratory, where he is a member of the Natural Language and Information Processing Research Group. He has a PhD in Computer Science and Artificial Intelligence from the University of Sussex, and a Philosophy degree from Cambridge. Previously he was a University Lecturer in Computer Science at Oxford University and a postdoctoral researcher at the University of Edinburgh. He works on a wide range of topics in Natural Language Processing, but his main research interest is syntactic and semantic analysis, with a focus on type-driven approaches (in particular Categorial Grammar) and the combination of symbolic and data-driven methods.