In this article we will review the three basic idioms to indicate possession in Common. The scope of this article is possessive constructions that reveal additional information about a noun, but where possession isn't the main topic of the sentence, as in English when we use possessive pronouns like 'my' - introducing information about possession as the main topic of a sentence will be for a future article.

Note that in idiomatic Common, people tend to avoid possessive constructions whenever possible, perhaps owing to the general awkwardness of referring to possession in Common, whereas in idiomatic English they're more often obligatory. When writing or speaking Common, the best rule of thumb is that if possession can be inferred from context and isn't essential to the meaning of what you're saying, you should omit it.

Possession was an intentionally verbose and roundabout feature of the Common language in Davidson's original design. The language still lacks a genitive case like the English apostrophe-s. The fictional society that Common was designed for was supposed to care only weakly about possession, but the real society that uses the language cares about possession very much. Since the language was created, two other possessive idioms have evolved to meet speakers' needs.

The three possessive forms are:

1. The periphrastic using 'su' plus a semitransitive verb of going or ownership with the possessor in the dative case (the dative idiom)
2. The periphrastic using the null preposition 'y', with the possessor as the nominative object of the null preposition (the nominative idiom)
3. Adposition of the possessor as the first modifying term in the noun phrase (the adposition idiom)

These idioms are in order of alienabiility, with the dative idiom seen as being the most alienable and the adposition idiom being the most inalienable possession. The is reflected in the order that they appear in the noun phrase, with the dative idiom using an 'Action' modifier being the farthest from the head term, the nominative idiom being a 'possessor' modifier and coming closer to the head term in sequence, and the adposition idiom sitting in the 'possessing terms' position, situated very close to the head term.

To give an idea of how these might be used, the dative idiom might apply if you are referring to comething like 'my hotel room' (you're just renting it), the nominative idiom might apply to 'my house' (that I own) and the adposition idiom might apply to a part of your body, like 'Tony's hand'. However, Common speakers do not honour this continuum reliably and real use cases are riddled with exceptions. Speakers may choose an idiom for clarity and flow more than to express alienability if alienability of possession is not especially important to the topic of conversation.

Dative Idiom

The dative idiom is the oldest possessive structure in Common, the one created by Davidson himself as the language's intended possessive idiom. It was created intentionally to deemphasize possession for a highly advanced and prosperous society that did not have a strong sense of personal ownership. It is the most verbose of the three, but is also capable of being the most precise. It tends to convey a high degree of alienability, and is more likely to be selected to convey that something is 'yours', but that you're just using it, you don't actually own it, if that contrast is important to what the speaker wants to express. It uses a relative clause with 'su', and fits into the Action slot in the Common noun modifier sequence. This means, in effect, that it will be with the last modifying phrases encountered after the head term.

The basic form of the dative idiom looks like this:

Na POSSESSEE su ija POSSESSOR nox [CLARIFYING VERB]

Basically, the possession is expressed in a relative clause introduced by su (absolutive case, every time), where the possessor is in the dative case and the verb is a semitransitive verb introduced by the auxilliary 'nox'. It is very common to stop there and not include a head term for the verb. The paradigm verb 'noxaj' can be used, so the idiom calques into English reads 'the thing that to the owner goes', or something like that. Alternatively, a semitransitive verb of possession can be used, like 'merit', to legally own, to further clarify the meaning of the construction, and as a normal relative clause, absolutely any kind of construction that can appear in this context can be used. Therefore, it is potentially the most flexible way to discuss possession.

Example:

A costo su ija pocuk nox se an uzre.
The(ABS) house that(ABS) the(DAT) child go(NP,IM) stand(NP,IM) be green.

'The child's house is green.'

Or with a clarifying verb:

A costo su ije nox merit se an uzre.
The(ABS) house that(ABS) I(DAT) go(NP,IM) own stand(NP,IM) be green.

'The house (that I legally own) is green'

Dative Idiom with Pronoun as the Possessor

To have a pronoun refer to the possessor is easy with the dative idiom. Simply drop the POSSESSOR head term and use the dative article alone. Example:

A costo su ijer nox se an uzre.
Our house is green.

The pronoun ijer is a paucal first person dative, which would be read as 'to us (exclusive)'.

Nominative Idiom

The nominative idiom developed very early in the early period of the language's history, possibly invented by fans and possibly by Davidson himself. It was actually attested in some later dialog on the show in an archaic form where the preposition 'y' was actually written. It is the most common idiom used today to indicate possession.

To make the nominative idiom, the possessor is associated with the possessee using the null preposition 'y', with the possessor as the object of y in the nominative case. The basic form looks like this:

Na POSSESSEE na POSSESSOR

The nominative idiom reads as less alienable than the dative idiom. The possessor clause can take any construction that any prepositional phrase can take, so it is possible so go into detail about the possessor, but less so about the nature of the possessive relationship in the way one can by including a verb with the dative idiom. It appears in the Possessor position in the Common noun modifier sequence, meaning that it would be encountered relatively late after the head term in order of prepositional phrases after the head term, but before any relative clauses.

Example:

A costo na pocuk se an uzre
The(ABS) house the(NOM) child stand(NP,IMP) be green

'The child's house is green.'

In Old Common, it would have been written 'A costo y na pocuk se an uzre'. Although we refer to this construction as 'using the preposition y' today, the 'y' is never written or spoken. We can see that the development of the modern form has given the nominative case a somewhat genitive (possessive) quality by default..

Nominative Idiom with Pronoun as the Possessor

To have a pronoun refer to the possessor is easy with the nominative idiom as well. Simply drop the POSSESSOR head term and use na alone, or replace it with the appropriate dative article. Example:

A costo wenar se an uzre.
Our house is green.

The pronoun wenar is a paucal first person nominative, which would be read as 'of us (exclusive)'.

With the nominative possessive idiom with pronouns, it is also sometimes seen that the speaker will throw in the dummy head term 'yn' even if it is not required, as this type of usage makes the pronoun more emphatic. This type of form like 'A costo wenar yn se an uzre' is more common in some local dialects than others.

The Adposition Idiom

The adposition idiom also developed very early in the early period of the language and is attested in the Hillbillies screenshow. To make the adpositive possessive, use the possessor as a modifying term to the possessee head term. If there are other modifying head terms, head terms indicating possession come first. Possession using this idiom is considered to be the least alienable type of possession. It is the most succinct, but also the most limited way to express possession. The basic form  looks like this:

Na POSSESSOR POSSESSEE

The issues with this form are that it can blur the line between a separate possessor and possessee, and the two forming a kind of compound word together, and depending on the possessor, can lead to ambiguous meanings. There is also no direct way to use it with pronouns, as pronouns are articles and cannot appear inside an article-head term bracket. It is more clear and unambigiuous if the possessor is a personal name rather than a general term.

The possessor fits into the Possessing Terms position in the Common noun modifier sequence, meaning it will come after any modifiers like adjectives. This will seem strange to English speakers, where an apostrophe-s genitive will come before modifying adjectives. The Common possessing term actually is more like a piece of a compound word than a genitive noun.

Example:

A pocuk costo se an uzre.
The child's house is green.

This form is the most succinct. The ability to modify the possessor pocuk or the type of possession is extremely limited. You can't readily convey any information about the child like number, for example - it could just as easily mean 'the children's house'. This form emphasizes a very inalienable type of possession if contrasted with other forms. The example given is also ambiguous. It could mean 'the child's house', or it could mean 'a house of or for children', like a play house. This has to be sorted out by context. However, with a personal name, this idiom is much more clear:

A Toni costo se an uzre.
Tony's house is green.

In this construction, it is clear that 'Tony's house' is meant. When this idiom is used, context is required to disambiguate. 

Adposition Idiom with Pronoun as the Possessor

It is not possible to directly use a pronoun as a possessor using this idiom. To get around this, one might use a noun that can stand in for the pronoun you want to say, such as a politeness head term instead of 'you', etc. These sorts of constructions are common. An example using the politeness head term 'sy':

A sy pikki se an sinku.
The(ABS) sir/ma'am cat stand(NP,IMP) be small/cute

'Your cat is cute'

This is a common polite formulation when addressing someone else.