The form of grammar rules

Grammar rules are intended to express generalisations about patterns in sentences (or words), in other words, about syntagmatic relations. We have seen that these patterns take the form of groupings of words, in which hierarchies of smaller and larger units are formed. The smallest units are - in many types of grammar - words. Words in turn consist of smaller units, the smallest being morphemes. In fact, in some grammar theories, the smallest units of sentences are morphemes, and words do not play a direct role at all.

The basic kind of grouping of words into phrases, or smaller phrases into larger phrases, is simply to summarise the fact that the larger unit, e.g. a sentence ``S'', consists of specific smaller units in a particular order, i.e. ``NP VP''.

Rules expressing this kind of pattern are called

• constituent structure rules,
• phrase structure rules, or, more technically,
• context-free rules.

They have the form:

S'' -> COMP S'

S'' -> S' and S''

S' -> NP VP

where S'' is the dominating complex sentence S' is the included sentence

and so one.

Tasks:

1. Discuss what other basic rules are necessary to describe English sentence patterns. To provide an empirical basis for this,
   1. invent sentences of different types and with different structures.
   2. analyse the sentences in the corpus ``The tiger and the mouse'' which ws discussed earlier.
2. Search the web for definitions of technical terms which are given in this section.