# Ownership exchange

Ownership in Xapagy is represented with a relation between the owner and the owned entity. The same concept applies to groups of relations such as physical containment, physical attachment, legal ownership and so on. The relationship is considered {\em active} as long as the relation VI is in focus. A relation VI can be expired from the focus, and a similar relation added later.

Let us now discuss how we can represent the exchange of ownership, for instance in the following snippet:

Johnny gives an apple to Mary.

This implies that there was an apple, which is in the ownership of Johnny. This is not an action, only a situation:

An apple / exists.
"Johnny" / has / the apple.
"Johnny" / gives / an apple.
"Mary" / thus receives / the apple.

The other challenge is that the English sentence has a subject (Johnny), a direct object (apple) and an indirect object (Mary). This can not be represented with a single VI, which at most allows a subject and an object.

The representation model splits the English statement into two VIs, one for Johnny giving the apple and the other one for Mary receiving it, but connects them with a coincidence link, which shows that these two VIs describe different aspects of a single event. The figure below shows the focus VIs for this exchange.

One of the consequences of this representation model is that we can represent situations where we know only one half of the statement. For instance, we can say:

Mary is given an apple.

An apple / exists.
"Mary" / receives / the apple.

The second VI will be shadowed by sentences of the given form, some of them having coincidence links to the VI pair which specifies that there is somebody who gave the apple. In the course of the normal operation of the Xapagy agent, this will appear as headless shadow suggesting a missing or predicted action – depending on other settings, the agent might or might not act on these suggestions.