A Bootstrapping Approach to Automatic Annotation of Functional Information to Adjectives with an Application to German Bernd Bohnet, Stefan Klatt and Leo Wanner Computer Science Department University of Stuttgart Breitwiesenstr. 20-22 70565 Stuttgart, Germany
[email protected] Abstract We present an approach to automatic classification of adjectives in German with respect to a range functional categories. The approach makes use of the grammatical evidence that (i) the functional category of an adjectival modifier determines its relative ordering in an NP, and (ii) only modifiers that belong to the same category may appear together in a coordination. The coordination context algorithm is discussed in detail. Experiments carried out with this algorithm are described and an evaluation of the experiments is presented.
1. Introduction Traditionally, corpora are annotated with POS, syntactic structures, and, possibly, also with word senses. However, for certain word categories, further types of information are needed if the annotated corpora are to serve as source, e.g., for the construction of NLP lexica or for various NLP-applications. Among these types of information are the semantic and functional categories of adjectives that occur as premodifiers in nominal phases (NPs) (Raskin and Nirenburg, 1995). In this paper, we focus on the functional categories such as ‘deictic’, ‘numerative’, ‘epithet’, ‘classifying’, etc. As is well-known from the literature (Halliday, 1994; Engel, 1988), the functional category of an adjectival modifier in an NP predetermines its relative ordering with respect to other modifiers in the NP in question, the possibility of a coordination with other modifiers, and to a certain extent, also the reading in the given communicative context. Consider, e.g. in German, (1)
category(ehemalig). In contrast, jung ‘young’ and dynamisch ‘dynamic’ belong to the same category; they can be permuted in an NP without an impact on the grammaticality of the example: (3)
and
Viele dynamische, junge Politiker ziehen aufs Land ‘Many dynamic, young politicians move to the country side’. They can also appear in a coordination: (4)
but
(2)
Viele ehemalige Politiker ziehen aufs Land ‘Many previous politicians move to the country side.’ but *Ehemalige viele Politiker ziehen aufs Land ‘Previous many politicians move to the country side.’
Jung ‘young’ and kommunal ‘municipal’, viele ‘many’ and ehemalig ‘previous’ belong to different functional categories, which makes them unpermutable in the above NPs and implies a specific relative ordering: category(jung) < category(kommunal) and category(viele)
