tailieunhanh - Constituent Structure - Part 24

Constituent Structure - Part 24 | 90 PHRASE STRUCTURE GRAMMARS AND X-BAR of a sentence can be composed from the meanings feature structures of the individual words. The information contained in PSRs Our survey of simple PSGs would not be complete without a look at precisely the kinds of information that phrase structure rules and their resultant constituent trees or P-markers represent. In the next chapter we will look at the various ways these kinds of information are either restricted or embellished upon by extending PSGs in various ways. Starting with the obvious simple PSGs and the trees they generate capture basic constituency facts representing at least the set of dominance relations. Such relations are marked by the arrows in the PSRs themselves. Equally obviously although frequently rejected later PSGs represent the linear order in which the words are pronounced. For example given a rule NP D N the word that instantiates the determiner node precedes the word that instantiates the N node this is represented by their left-to-right organization in the rule. In versions of PSG that are primarily tree-geometric rather than being based on P-markers or RPMs the tree also encodes c-command and government relations. Less obviously but no less importantly phrase structure rules contain implicit restrictions on which elements can combine with what other elements Heny 1979 . First they make reference to primitive non-complex syntactic categories such as N V P Adj and D and the phrasal categories associated with these NP VP AdjP etc. Next they stipulate which categories can combine with which other categories. For example in the sample grammar given much earlier in 14 there is no rule that rewrites some category as a D followed by a V. We can conclude then that in the fragment of the language that this grammar describes there are no constituents that consist of a determiner followed by a verb. Phrase structure rules also at least partly capture subcategorization relations for example the category .