verb run has an obligatory argument, its subject (a DP agent), which must appear in the sentence. The following subcategorization frame for the verb run specifies its properties. The subcategorization frame of run is as follows: run Verb, [DP agent __ ] An adverb such as fast has its own subcategorization frame: fast Adverb, [VP_] It is out of this frame that a sentence like the following can be generated: John runs fast. If either of these subcategorization frames are violated, so is the projection principle, and the utterance would be ill-formed: *Runs fast. *John fast. Before the projection principle was proposed, phrase structures were generated in separation from the properties of lexical entries. These were hypothesized to enter the slots in pre-generated structures waiting to be filled by the lexical material. According to more recent theories, phrase structures are not generated by phrase structure rules, but are "projected" from the lexical entries. The projection principle therefore obviates the need for phrase structure rules in the generative component. In 1982, Noam Chomsky proposed the extended projection principle as an addendum to the projection principle. Locality of Selection Locality of Selection states that properties of lexical items must be satisfied locally within their domain. The local domain is characterized by being the smallest XP with a subject (WP). The properties of the constituent are chosen by the constituent head. A constituent will be incorrect if the lexical requirements are not satisfied. Locality of Selection ensures that when the projection principle occurs, it is satisfied locally (This explains why in the above example; N, N', and NP appear immediately above John). We see examples of this with certain verbs. With a verb such as “hit” you need a DP that it selects for: *Mary hit Mary hit [DP the ball] In a local domain there are three main levels. The head (X) of the local domain is at the bottom which projects up to and X bar level and then to the XP level. Each head can select for a complement. The X bar level can select for a specifier and the XP level can select for an adjunct. This makes up the basic structure of a local domain. The components of the tree are organized hierarchically. Along with this, the adjunct (YP), specifier (WP) and complement (ZP) are all optional and only used when required An important thing to acknowledge is