Construction meets computer: A Sign-Based Construction Grammar for Dutch
In this paper, we investigate into the use of cognitive constructionist approaches for formal, computational linguistics. We will raise the question of which elements of CxG can possibly help to improve state of the art-systems, and which elements probably cannot. In order to illustrate the advantages of the constructionist approach, we will outline a couple of stumble blocks for NLP, in particular multiword expressions, and discuss previous approaches to them. We then postulate that a formal approach that is based on constructionist ideas can deal with certain problems more elegantly and efficiently.
In order to illustrate the limitations of CxG, we will show how the tenet of "meaningful phrasal patterns" runs into problems in a formal constraint-based model for parsing/generating and on which points the proposed model potentially breaks. The alternative analysis we introduce, follows the lines of Sign-Based Construction Grammar (Sag, Wasow & Bender 2003, Sag 2005), and show how such an approach can overcome the previously mentioned problems. The major advantages of the model are, on the one hand, the fact that all items, i.e. lexical entries, lexical and grammar rules and general constraints on well-formedness are modelled as subtypes of the type feature structure. That allows for a strictly uniform way of capturing the combinatorial mechanisms. On the other hand, all items are modelled as signs, with a DAUGHTER that specifies the input and a MOTHER that specifies the output. This way of modelling offers the opportunity to put constraints on all levels of construction, as, e.g., on the semantics of the MOTHER in non-compositional cases.
We will report on work in progress, namely the implementation of such a model for a fragment of Dutch. Furthermore, we will touch upon the question how the cognitive constructionist tenets map upon the formal model, in order to illustrate that the difference between the approaches is smaller than it appears at first sight.
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Sag, I.A., Wasow, T., and Bender, E. (2003). Syntactic Theory. Second Edition. Stanford: CSLI Publications.
Sag, I.A., Baldwin, T., Bond, F., Copestake, A., and Flickinger, D. (2001). Multiword Expressions: A Pain in the Neck for NLP. LinGO Working Paper No. 2001-03.