Incremental construction and maintenance of morphological analysers based on augmented letter transducers

We define deterministic augmented letter transducers (DALTs), a class of finitestate transducers which provide an efficient way of implementing morphological analysers which tokenize their input (i.e., divide texts in tokens or words) as they analyse it, and show how these morphological analysers may be maintained (i.e., how surface form–lexical form transductions may be added or removed from them) while keeping them minimal; efficient algorithms for both operations are given in detail. The algorithms may also be applied to the incremental construction and maintentance of other lexical modules in a machine translation system such as the lexical transfer module or the morphological generator.