Constructing lexical transducers

INTRODUCTION A lexical transducer, first discussed in Karttunen, Kaplan and Zaenen 1992, is a specialised finite-state automaton that maps inflected surface forms to lexical forms, and vice versa. The lexical form con- sists of a canonical representation of the word and a sequence of tags that show the morphological characteristics of the form in question-and its syntactic category. For ex- ample, a lexical transducer for French might relate the surface form veut to the lexical form vouloir+IndPr+SG+P3. In order to map between these two forms, the trans- ducer may contain a path like the one shown in Fig. 1. v o u 1 o i r +IndP+SG+P3 v e u t Fig. 1 Transducer path as well. as generation (vouloir+lndP+SG+P3 - veut ). Analysis and generation differ only with respect to the choice of the input side (surface or lexical). The transducer and the analysis/generation algorithm are the same in both directions. Other advantages that lexical transducers have over other methods of morpho