Pushdown Stores and Subscripts

V a ~ r i o u s d e v i c e s f o r t h e imp r o v e m e n t o f p h r a s e s t r u c t u r e g r a m m a r s (PSG) h a v e b e e n s u g g e s t e d r e c e n t l y . I n p a r t i c u l a r , t h e PSG m o d e l w i t h a p u s h d o w n s t o r e ( P S G / P D S ) a s d e s c r i b e d b y V o Y n g v e , a n d t h e PSG w i t h s u b s c r i p t s ( P S G / S ) a s d e s c r i b e d b y G o H a r m a n a r e c o n s i d e r e d . It is contended that such devices, even if they may do away with some of the difficul_ ties of PSG, do not contain sufficient gene_ rative power to produce the structurally corn_ plicated sentences that are generated by other gramma rs (e.g., of transformational type). The handling of multiple disco,Ltinuous con_ stituents (DC) in PSG/PDS, as well as the use of :leletion rules in PSC./S is examined and criticized. It is shown that the improvements on PSG will not allow the grammar to generate a ii the sentences of the language that a trans_ formational grammar (TG) does; moreovdr, the improvements on PSG a re obtained only at the cost of introducing too much power at the PS level, so that the improved gr;~mmars in some cases will exceed the requirem@nts of the de_ scription, i.e. generate non_grammatical sent_