Concepts definition

In order to define an entity the tool accepts the following format:

DEFINITION -> ("A" | "An") ENTITY_NAME "has" ATTRIBUTES

Example:

A movie has an id, and a time duration.

In this example:

movie is the name of the entity;

id, and time duration are the attributes.

Therefore, every time movie is used, it is recognised as an entity with id and time duration as attributes.

Attributes and names can be made of letters, numbers and “_” (underscore). Note that attribute names can also be multiple words and have to start with a lowercase letter.

Moreover, yuo can define some attributes as keys as in the following example:

A movie is identified by an id, and has a name, and a duration.

In this case, id is saved as a key that is the attribute that identifies movie.

Why keys? Intuitively, keys are the attributes that identify a concept. The tool also supports a sort of inheritance concept, you can define a concept as an attribute of another concept. Consider the following example:

A location is identified by an address, and by a number.
A city is identified by a name, and has a location.

This results in city having as attribute a name, a location address and a location number, since location is identified by an address and a number.

Moreover, the concepts defined here can be used to define new concepts (see Defining new concepts). These derived concepts can be not declared here and will have some primitives entities as condition, in this case, the tool creates the new definition starting from the keys of the primitives.

Corresponding ASP:

A concept definition does not have an actual ASP translation. Here, you are defining the structure of the atoms, their predicates and fields. This is saved in memory, and the tool will recall these structures to rewrite the CNL into ASP.