Compilation of automata from morphological two-level rules

The t w o l e v e l m o d e l is a f r am ew or k for de s c r i b i n g word inflection. The model consists of a lexicon system and a formalism for two-level rules. The lexicon system defines all p o s s i b l e l e x i c a l r e p r e s e n t a t i o n s of w o r d f o r m s w h er ea s the r u le s ex pr es s the p e rm it te d r e l a t i o n s b e tw ee n l e xi ca l and surface representations. Word recognition is thus reduced into the question of finding a permissible lexical representation which is in a proper relation to the surface form. Similarly, generation is the inverse where the lexical representation is known and the task is to find a s u rf ac e r e p r e s e n t a t i o n which is in a proper relation to it. Within the two-level model these relations pertaining to the ru le co m p o n e n t h a v e been e x p r e s s e d in two ways. A rule f o r m a l i s m has been used for c o m m u n i c a t i n g the idea of the r u l e s , w h e r e a s the a c t u a l i m p l e m e n t a t i o n s h a v e b e e n a c c o m p l i s h e d by h a n d c o d i n g the r u l e s as f i n i t e s t a t e automata. The close connection between rules and finite state machines has facilitated this hand-coding. Expressing rules as numbers in a transition matrix is, of course, not optimal. Although it has proven to be feasible, it is tedious. It also tends to distract the linguist's thoughts from m o r p h o p h o n o l o g i c a 1 v a r i a t i o n s to t e c h n i c a l matters. Furthermore, hand c o m p i l e d a u t o m a t a are often not quite c o n s i s t e n t with intended rules. D i s c r e p a n c i e s arise because the design of rule automata is often affected by assumptions