Information Processing Theory Al 



to Billy by Johnny." Surely, since both are equivalent, we are 

 just complicating things by allowing two grammatical forms. In 

 algebra we do not have a symbol \ as in "B\A," which means 

 the same as "A/B", but we may say in English "B divided into 

 A" as well as "A divided by B." 



To explain these and many other aspects of English grammar, 

 Yngve postulates a mechanism for sentence production. Assume 

 that the brain has a large memory in which are stored rules such 

 as S = NP + VP; NP = T + N; VP = V + A; T = the; T = a; 

 A = away; V = went; V = ran; N = man. Such rules define a 

 grammar in that they can generate sentences if used in the fol- 

 lowing fashion: 



S = NP + VP 



-T+N+V+A 

 = the man went away 

 or S = a man ran away 



By selecting various rules, we may generate various sentences, all 

 grammatical. 



However, in order to generate sentences in the prescribed left- 

 to-right fashion, it is necessary that we complete the expansion 

 of the left-most phrases while "keeping" our place," i.e., remem- 

 bering the higher order rules which are guiding" the sentence 

 production. If we had a scratch pad on which to keep our place, 

 its contents at various staoes mio'ht look like this: 



