2.1.7 Rules

Such rules are known as rewrite rules as they describe how to draw a tree by ‘re-writing’ the symbol on the left of the arrow for the symbols on the right. Thus, if we start with the S at the top of the tree diagram we can rewrite this as a DP and a VP. The VP can be re-written as a verb, a DP and a PP and the PP as a preposition and a DP. The DPs can then be re-written as determiners followed by nouns.

2.1.7 Rules

Although the system of rules in (36) is capable of describing the structures of a good number of English sentences, it is clear that we would need many more rules to attempt to describe the structures of all English sentences. For example, not every DP is made up of a determiner followed by a noun. Some may contain just a determiner, such as this for example, or a determiner, an adjective and a noun, such as a rusty kettle. A DP may indeed contain, amongst other things another sentence, such as the diagnosis that she had flu. It is clear that we would need many rewrite rules to capture all the possibilities for English DPs.

3.1.1 Rewrite rules and some terminology

3.1.5 Adjuncts

It is now time to turn to the third rule in (1), which we repeat here:

3.1.5 Adjuncts

This is different from the previous two rules in a number of ways. First, the previous rules specified the possible constituents of the various specific projections of the head: complements are immediate constituents of X' and specifiers are immediate constituents of XP. The adjunction rule in (30) is more general as it states the possible constituents of an Xⁿ, that is, an X with any number of bars. In other words, Xⁿ stands for XP (=X''), X' or X (=X⁰). The adjunct itself is defined either as a word (Y) or as a phrase (YP) and we will see that which of these is relevant depends on the status of Xⁿ: if Xⁿ is a word, then the adjunct is a word, if not then the adjunct is a phrase.

3.1.5 Adjuncts

Note that the two elements on the right of the rewrite arrow are separated by a comma. This is missing from the complement and specifier rule. The significance of the comma is to indicate that the order between the adjunct and the Xⁿ is not determined by the rule. We have seen that in English the complement follows the head and the specifier precedes it. Adjuncts, on the other hand, it will be seen, may precede or follow the head depending on other conditions, which we will detail when looking at specific instances of adjunction.

3.1.5 Adjuncts

The final thing to note is that the adjunction rule is recursive: the same symbol appears on the left and the right of the rewrite arrow. Thus the rule tells us that an element of type Xⁿ can be made up of two elements, one of which is an adjunct and the other is another Xⁿ. Of course, this Xⁿ may also contain another Xⁿ, and so on indefinitely. In this way, any number of adjuncts may be added to a structure.