A transformational rule is a rule which requires or allows us to perform certain changes in the kernel structure. The product of a transformation is a transform It retains the grammatical and semantic relations of the kernel sentence it is derived from.
"A transformational rule tells us how to derive something from something else by switching things about, putting things in or leaving them out, and so on."
The transformational rules may be called also 'derivation rules' because they tell us how a variety of sentence structures and nominal structures are derived or generated from the kernel sentences.
E. g., from the kernel word 'love' a number of derivative words can be generated by means of certain rules, telling us what morphemes must be added and to what kernel they must be added (V or N):
  love (N)
| love (V) | |
| lovely (A) |   loving (A)
| lovingly (D) |
| loveliness (N) | lovable (A) | |
| loveless (A) | beloved (A) | |
| lover (N) |
This shows that the kernel of a word may generate about ten new words. A kernel sentence structure also gives out a number, and an even much larger number, of derived transforms.
 S NP
|  S S
|
| the work of the machine | The machine does work. |
| the machine's work | Does the machine work? |
| the machine work | What works? |
| the working machine | The machine does not work. |
| for the machine to work | The machine did not work, etc. |
| the machine's working | 
|
| the machine working |
| |||
 |
S1 + S2 S3
The machine works and hums.
When the machine works it hums.
Working, the machine hums.
When (while) working the machine hums.
I like when the machine works.
If the machine worked!
etc.
The study of the transformational rules will come to the reader in three steps.
First one must study the transformations in simple sentences, then the two-base transformations (compound, semi-compound, complex, semi-complex sentences) and the transformation of nominalization.
Transformations in simple sentences produce such transforms that are also simple sentences: S S.
The transformations of the simple sentences can be divided into two types: obligatory transformations and optional transformations. Obligatory transformations are transformations on the morphemic level, whose application is indispensable for building up a sentence. They generate intra-model transforms within one and the same model.
* * *
These transformations are generally designated as T-AUX (AUX stands for the word auxiliary'). T-AUX involves the following changes of the finite V:
(1) the choice of the tense;
(2) the choice of number and person: the addition of the -s suffix if the V is in the present tense, if the NP is singular, 3rd person; the zero-suffix if the NP is plural " John has been laughing "; " The boys have been laughing ";
(3) the choice of modality: the addition of a modal verb (" The boys must have been laughing "; " The boys will be laughing "; " They ought to be crying "),
(4) the choice of aspect;
(a) the addition of the discontinuous m orpheme 'have -en' (" You have seen that ");
(b) the addition of the discontinuous morpheme 'be-ing' (" She was smiling ").
We must note that some modern linguists do not extend the term 'tense' to the phrasal constructions (such as 'is writing', 'has written' and others), they reserve the term 'tense' for those expressed in the verb itself, thus recognizing only two tenses in the English verb: present and past. The phrasal constructions are considered to be 'aspects' (with 'have- еn ' and with 'be- ing ') and modals ('will do', 'shall ask', 'can go', etc.), all these also have two tenses.
The general formula of the grammar of the finite verb reflecting the T-AUX, is:
AUX -+ tense (M) ('have - en ' ('be - ing ') - { V / BE }
The sign V / BE shows that all these transformations on the morphemic level can be applied to verbs and to the word BE.
The sign M shows that one of the modal verbs can be added: can, may, will, shall, must, ought to.
The sign AUX stands for tense (present or past). Tense applies to whatever follows it in the verbal phrase (only 'must' and 'ought' do not change). It also involves the number and person transformations:
V
 | |||
 |
Be
 | ||||
 | ||||
 | ||||
Each grammatical morpheme must be added to the end of the following element. Thus if you choose to construct a sentence in the present with the V, say, 'walk', you will begin it in the following way: The man—you don' t need expressing modality so you discard (M)—and add -s to the element 'have', and so get 'has'; the next element - en should be added to 'be', and you get 'been'; the next element in the diagram is - ing which is added to the V 'walk' yielding 'walking', and the whole form of the V will appear as "The man has been walking."
The same rules can be applied to BE. "He must be here." "I am being polite." "I must have been here before." "He has been absent for a week."
This T-AUX is an obligatory transformation which applies to all kernel sentences.
There is a special rule for the ' N is N ' kernel structure which consists in adding -s to both the N in the construction when the V is also plural, i. e. 'are', 'were', 'have been'. E. g. "The girls are friends." "These ladies are actresses."
* * *
Optional transformations in simple sentences are transformations on the syntactic level or, on the word class level. An optional transformation may be chosen by the speaker depending on the purpose of communication (question, command, exclamation). An optional transformation results in a transform which is not a kernel sentence any longer.
A kernel sentence is a declarative one, it relates about facts. Such a sentence can be transformed into an affirmative sentence which affirms a statement more intently; it also can be transformed into a negative sentence. Both these transforms can be further transformed into interrogative sentences or questions, so that these may be either affirmative questions or negative question.
In sentences with HAVE the V HAVE is stressed. But there is a tendency to introduce the function ' do ' into sentences with HAVE, e. g. "And I did have fun". "He does have a family".
T-NOT designates a negative transformation. The procedure here consists in introducing the function word 'not', or its phonetical variant 'n','t', which put after DO, BE, HAVE or some modal (M) and is sometimes fused with them. E. g. " She did not see him. " " The girl didn 't see him. " " She was not (wasn 't) happy. " " He has not (hasn 't) come. " " Don't you like it? " " Haven't you seen him?"
There are some other ways of constructing negative transforms:
1. With negative substitutes:
"Somebody saw that Nobody saw that"
"I saw a man there I saw none there"
2. By introducing negative function words, such as 'never', 'nowhere':
"You can tell You never can tell"»
"I see him there I see him nowhere"
