Trees that won't grow

Just as speakers know whick structures and strings of words are permitted by the syntax of their language, they know which are not. Such knowledge is specified implicitly by the phrase structure rules.

Since the rule S --- NP VP is the only S rule in our (simplified) grammar of English, the following word sequences and their corresponding structures do not constitute English sentences.

Note : Non-pertinent parts of the tree are sometimes omitted, in this case the Det and N of the NP, a buffalo.

Similarly, boy the

cannot ba an NP in English because no NP rule of English syntax specifies that a determiner can follow a noun.