Using Meta-Morph Rules to develop Morphological Analysers: A case study concerning Tamil

摘要

This paper describes a new and larger coverage Finite-State Morphological Anal-yser (FSM) and Generator for the Dra-vidian language Tamil. The FSM has been developed in the context of com-putational grammar engineering, adhering to the standards of the ParGram effort. Tamil is a morphologically rich language and the interaction between linguistic anal-ysis and formal implementation is complex, resulting in a challenging task. In order to allow the development of the FSM to fo-cus more on the linguistic analysis and less on the formal details, we have developed a system of meta-morph(ology) rules along with a script which translates these rules into FSM processable representations. The introduction of meta-morph rules makes it possible for computationally naive lin-guists to interact with the system and to expand it in future work. We found that the meta-morph rules help to express lin-guistic generalisations and reduce the man-ual effort of writing lexical classes for mor-phological analysis. Our Tamil FSM cur-rently handles mainly the inflectional mor-phology of 3,300 verb roots and their 260 forms. Further, it also has a lexicon of approximately 100,000 nouns along with a guesser to handle out-of-vocabulary items. Although the Tamil FSM was primarily developed to be part of a computational grammar, it can also be used as a web or stand-alone application for other NLP tasks, as per general ParGram practice.