Bundt User's Manual · Bundt Toolset version 1.0.1.0

Existence Qualification

An object in an instance model, by default, represents the fact that some entity exists in the world. No statement is made about when this entity exists or according to whom; it is assumed that it exists always or in the present moment, and that this existence is agreed to by everyone.

By using existence qualification, we can explicitly state when it is that something exists, and/or who thinks that this is so.

Details

Without existence qualification, an object indicates that something exists, but it is not said when it exists or who thinks it exists. It is often assumed that the time span of this existence is not relevant, or that it occurs in the present (which, in itself, is quite ambiguous), or that it always exists. Similarly, it is often assumed that every person that is relevant to the model (authors, audience, etc.) agree that this entity exists. Sometimes, this is good enough. But, in some situations, we may need to state clearly in which moment something exists, and/or who agrees to such an existence. To do this, we qualify the object with one or more existential qualifiers.

An existential qualifier is another object that has temporal or subjective semantics, that is, it represents a moment or span in time, or an agent capable of perception and cognition. A temporal existential qualifier, for example, may represent a particular date/time, a well known event such as the Second World War, or a period such as the Middle Ages or the Spring of 1972. Similarly, a subjective existential qualifier may represent a particular person, a group, a community or an organisation.

Existential qualification is a complex topic, and can't be fully described here. Please refer to the ConML Technical Specification for additional details.

Using existential qualifiers

Let's assume that b is an object of the Building class representing a specific building, and SWW is an object of the Event class representing the Second World War. By writing b@SWW we are attaching the existential qualifier SWW to b through the temporal qualification operator @ (which is read as "at"). This means that the building b exists only at the time of the Second World War, and it doesn't exist at other times.

Similarly, let's assume that p is an object of the Person class representing a particular individual. By writing b$p we are attaching the existential qualifier p to b through the subjective qualification operator $ (which is read as "according to"). This means that the building b exists only according to p, and other people may disagree of its existence.

Aspect classes

The objects that work as predication qualifiers must be instances of the corresponsing aspect class.

Existence Qualification

Details

Using existential qualifiers

Aspect classes

See Also