Predicate¶

Definition¶

<predicate name="r" sort="s"/>

A predicate ascribes some property to an individual. This individual is the argument of the predicate. A predicate requires its arguments to be of a specific sort.

Parents¶

• <ontology>

Children¶

None.

Behaviour¶

A predicate ascribes some property to an individual. This individual is the argument of the predicate. A predicate requires its arguments to be of a specific sort.

If there is a sort hour, whose individuals are integers in the range 0-23, there can be one predicate current_hour, and another one alarm_hour, of the sort hour. The first one is a part of the description of the current time, the sencond one i a part of the description of the current alarm time.

Predicates in TDM typically take a single argument of a specified sort (i.e. they have arity 1). Predicates that do not take an argument (arity 0), have sort Boolean.

Predicates can be features of other predicates. This is particularly useful for incremental search dialogue. For example, if each product belongs to a product category, one might want to search for products based on their category (among other things). To do this, the predicate for product category is defined as a feature of the predicate for products.

Examples¶

Name of person to call¶

<predicate name="name_to_call" sort="name">

Selected product predicate, with a feature predicate for product category¶

<predicate name="selected_product" sort="product"/>

<predicate name="selected_category" sort="category" feature_of="selected_product"/>