According to quirk, case is the “gramatical category that can express a number of different relationships between nominal elements”. In English there are two cases: a common case, and a genitive case.
Singular nouns add ´s to form the genitive.
In words ending in the letter s, or other spelling pronounced /z/ or /s/, the s is omitted.
This is the case of some greek names (Hercules, Xerxes).
In other names ending in /z/, like Burns, both options are correct (Burns´ / Burns´s, Dickens´ / Dickens´s).
In the phrase for ….. sake, the genitive is omitted when the noun ends in /s, z/ (for goodness´ sake, for conscience´ sake).
Plural nouns ending in –s, the s is omitted: the boys´ house.
Z after voiced non-sibillants boy´s /boiz/
S after voiced non-sibillants cat´s /kats/
Iz after sibilants horse´s /ho:ziz/
MEANING OF THE GENITIVE
Subjective. The genitive may denote the agent of the headword, when it denotes an action. The master´s work.
Objective. The genitive denotes the receiver of the action. The president´s drivers. (it is preferred “of”: the drivers of the president).
Origin genitive: my mother´s country
Descriptive genitive: a summer´s day. A doctor´s degree.
FUNCTIONS OF THE GENITIVE
ATTRIBUTIVE FUNCTION: It is the most common function, it precedes a headword, and it is subordinated to it. John´s house.
It can be specifying (it refers to a particular person or thing). My mother´s house.
It is pronounced with two strong stresses The ´teacher´s ´book.
The attributive words preceding the genitive refer to the genitive. My dear friend´s house.
Or it can be classifying. It refers to a class or kind. A doctor´s degree.
It is pronounced with one strong stress: a ´doctor´s degree.
The attributive words preceeding the genitive refer to the group as a whole: A foreign doctor´s degree. (it is not the doctor who is foreign).
This kind of genitive tends to form set phrases, as statesman, or bridesmaid.
INDEPENDENT FUNCTION. The headword is not expressed.
Elliptic: the headword is not expressed because it is in the context. Mary´s is a beautiful house.
Local genitive: It is implied that the headword is a place, usually a house, an institution, a business, or a shop. My uncle´s (house), Saint Andrews´ (church), butcher´s (shop), the butcher´s (shop).
POST GENITIVE OR DOUBLE GENITIVE
Sometimes, both the construction with “of”, and the genitive are used at the same time: two friend´s of tom´s. There can be differences between this construction and a normal genitive:
When we talk about a portrait of my father, we think in a portrait representing him, whereas if we talk about a portrait of my father´s, it is implied that my father owns the portrait, or it was made by him.
GENITIVE AND OF CONSTRUCTION
We can only use the genitive in the following cases:
When the noun is a name of relation without a preceding attributive word:
Mother´s birthday *the birthday of mother
Classifying genitives have not, as a general rule, an of construction counterpart:
A giant´s task does not mean the same as a task of a giant. The kid made a professional player match. (not the game of a professional player).
If the noun denotes time, the of construction is not usually used:
A day´s work. A month´s holiday.
Post-genitive and local genitive have no of construction counterpart.
There are some set phrases using the genitive: at arm´s length, at bird´s eye.
On the other hand, the of construction is preferred in the following cases:
If the noun denotes a thing: the colours of the rainbow.
If we want to avoid ambiguity between singular and plural:
The teachers´ task / the task of the teachers.
Adjectives used substantivally are not normally used in the genitive:
The English´ habits / the habits of the English.
There are two series:
Attributive: my, your, his, her, its, our, your, their.
The predicative: mine, yours, his, hers, ours, yours, theirs.
Unlike many other languages (including Galician and Spanish), English uses possessives to refer to parts of the body and personal belongings:
She has broken her arm.
He put his hand into his pocket.
The definite article is however used in prepositional phrases concerned with the object:
She took me by the hand, she palmed him on the shoulder.
OTHER POSSESSIVE STRUCTURES
Nouns can modify other nouns with a meaning similar to the genitive: a police car, theatre chairs.
Some verbs denote possession:
Have. He has got money.
Belong. It has a more legalistic sense: the money belongs to him. It also means “to be a member”. He belongs to this club.
Own. It also has a legalistic sense. He owns two buildings in the city.
Possess: it has an official sense. He doesn´t possess any degree.
Lack: it means “not to have”.
Others: include, exclude, contain.
Possessive relative: whose.