THE TRANSFORMATIONAL COMPONENT
5.1 Highlight the power of transformational rules
Having seen that phrase structure rules have various limitations and that what they produce are not real sentences, we need other rules that are capable of giving us actual sentences. These are transformational rules (henceforth T rules). As the name suggests, T rules bring about change.
THE POWER OF TRANSFORMATIONAL RULES
We have already said that T rules change one type of sentence into another. The process involved looks like this:
Phrase structure rules -> deep structure sentences -> rules-> surface structure
This means that we start off with phrase structure rules (rewrite rules + the lexicon) which enable us to produce deep structure sentences which are then changed/transformed by T rules into surface/ actual sentences. T rules bring about this change by:
- substituting items for
PS rules are not capable of doing any of these things. Transformational rules have two parts, namely structural description (SD) and structural change (SC). The SD is a sequence of symbols before any transformation is applied. It is therefore what is produced by rewrite rules. On the other hand, the SC is a sequence of symbols showing the changes that have occurred after a T rule has been applied. To illustrate how this works, let us begin by looking at the Affix Hopping Transformation.
THE AFFIX HOPPING TRANSFORMATION
The affix hopping transformation is also referred to as the flip-flop transformation. Basically it involves the movement of verbal affixes. Consider the sentence:
The students had been reading.
The rewrite rule for the Aux is: Aux -> tense + (have + en) + (be + ing ). Tense is past. As you can see, we have begun with an affix (tense is an affix) followed by a verb (have), then an affix (-en), followed by a verb (be) and then an affix (-ing). We can therefore summarise this information and say that in the structure of the Aux, the order is Affix + Verb. This is the SD or deep structure representation. Recall that it is necessary to have this representation in order to show which constituents are more closely related to each other in expressing, for example, the progressive aspect. But we obviously realise that no actual English sentence looks like that (If we attempt to pronounce it, we will end up with “tense haveen being”). We therefore need to perform a transformation that will give us the natural order of constituents in a sentence. The T rule involved will move or rearrange the verbal affixes in the following ways: The tense affix will now attach to ‘have’ to produce the past tense verb ‘had’. ‘have’ will not move since it is a full verb and not an affix. Next to move will be the affix ‘–en’. It will attach to the verb ‘be’ to produce ‘been’. Being a full verb, ‘be’ will not move but the affix ‘-ing’ will. It will attach to the main verb ‘read’ to produce ‘reading’. After these movements, the structure of the Aux will be Verb + Affix– hence have + past tense, be + en , read + ing. This is now the SC. How has this come about? The affixes have hopped / jumped from the left side of a verb to the right side of it- hence affix hopping or flip-flop transformation which yields ‘had been reading’. A phrase-marker showing the said movements appears below.