This idea was proposed by Krauwer and des Tombe ( 1981 ) , Langendoen and Langsam ( 1987 ) , and Pulman ( 1986 ) , and was rediscovered by Black ( 1989 ) and recently by Johnson ( 1998 ) .
finitestate approximation of constraintbased grammars using leftcorner grammar transforms
Mark Johnson
By restricting the height of the stack of a pushdown automaton , one obstructs recognition of a set of strings in the context-free language , and therefore a subset approximation results . This idea was proposed by Krauwer and des Tombe ( 1981 ) , Langendoen and Langsam ( 1987 ) , and Pulman ( 1986 ) , and was rediscovered by Black ( 1989 ) and recently by Johnson ( 1998 ) . Since the latest publication in this area is more explicit in its presentation , we will base our treatment on this , instead of going to the historical roots of the method .
This idea was proposed by Krauwer and des Tombe ( 1981 ) , Langendoen and Langsam ( 1987 ) , and Pulman ( 1986 ) , and was rediscovered by Black ( 1989 ) and recently by @@CITATION .