A Unification-based Approach to Morpho-syntactic Parsing of Agglutinative and Other (Highly) Inflectional Languages

A Unification-based Approach to Morpho-syntactic Parsing of Agglutinative and Other (Highly) Inflectional Languages G~ibor Pr6sz6ky proszeky@morphologic.hu MorphoLogic K6smdrki u. 8. Budapest, Hungary, H-1118 http://www.morphologic.hu Bal~tzs Kis kis@morphologic.hu Abstract This paper introduces a new approach to morpho-syntactic analysis through Humor 99 (High-speed Unification Mo.rphology), a re- versible and unification-based morphological analyzer which has already been integrated with a variety of industrial applications. Hu- mor 99 successfully copes with problems of agglutinative (e.g. Hungarian, Turkish, Esto- nian) and other (highly) inflectional lan- guages (e.g. Polish, Czech, German) very ef- fectively. The authors conclude the paper by arguing that the approach used in Humor 99 is general enough to be well suitable for a wide range of languages, and can serve as basis for higher-level linguistic operations such as shallow parsing. Introduction There are several linguistic phenomena that are possible to process by means of morphological tools for agglutinative and other highly inflec- tional languages, while processing the same fea- tures requires syntactic parsers in case of other languages such as English. This paper provides a brief description of Humor 99 first presenting a general theoretical background of the system. This is followed by examples of the most recent applications (in addition to those listed earlier) where the authors argue that the approach used in Humor 99 is general enough to be well suitable for a wide range of languages, and can serve as basis for higher-level linguistic operations such as shallow or even full parsing. 1 Affix arrays rather than affixes Segmentation of a word-form in Humor 99 is based on surface patterns, that is, typical sequen- ces of separate suffix morphemes are analyzed as a whole. For example, the English nominal end- ing string ers' (NtoV+PL+POSS) is a complex affix handled as an atomic string in Humor 991 . The string ers' is generated from er+s+ 's in an earlier development phase by a dedicated utility. The generator is able to make a finite set of affix sequences from an (even recursive) description 2. Running this utility can be considered the learn- ing phase of the algorithm. The resulting suffix combinations are stored in a compressed internal lexicon structure that guarantees very fast searching) The entire algorithm shows features similar to the hypothesis according to which most segments of word-forms in agglutinative lan- We use mainly English examples in spite of the fact that English morphology is simpler than the morphologies of agglutinative and highly inflectional languages. 2 Depth of the recursive process can be given as a parameter. The method is similar to the one of Goldberg & K=ilm=in (1992) used in the BUG system: the description is theoretically infinite, hut there is a finite performance limit when running. 3 The idea has something in common with the PC-Kimmo based analyzer of the University of Pennsylvania (Karp et al. 1992). Our compression ratio is around 20%. 261 guages are handled as "Gestalts" by native speakers, instead of parsing them on-line. 4 This idea is not new in the literature: according …

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