Top Down
An important aspect of phrase structure rules is that they view sentence structure from the top down. The category on the left of the arrow is a greater constituent and the immediate constituents to the right of the arrow are lesser constituents. Constituents are successively broken down into their parts as one moves down a list of phrase structure rules for a given sentence. This top-down view of sentence structure stands in contrast to much work done in modern theoretical syntax. In Minimalism for instance, sentence structure is generated from the bottom up. The operation Merge merges smaller constituents to create greater constituents until the greatest constituent (i.e. the sentence) is reached. In this regard, theoretical syntax abandoned phrase structure rules long ago, although their importance for computational linguistics seems to remain intact.
Read more about this topic: Phrase Structure Rules
Famous quotes containing the word top:
“... when you make it a moral necessity for the young to dabble in all the subjects that the books on the top shelf are written about, you kill two very large birds with one stone: you satisfy precious curiosities, and you make them believe that they know as much about life as people who really know something. If college boys are solemnly advised to listen to lectures on prostitution, they will listen; and who is to blame if some time, in a less moral moment, they profit by their information?”
—Katharine Fullerton Gerould (1879–1944)
“We fight our way through the massed and leveled collective safe taste of the Top 40, just looking for a little something we can call our own. But when we find it and jam the radio to hear it again it isn’t just ours—it is a link to thousands of others who are sharing it with us. As a matter of a single song this might mean very little; as culture, as a way of life, you can’t beat it.”
—Greil Marcus (b. 1945)