The Predicates Section
Must declare clauses in a predicates section.
When you declare a predicate, you tell Visual Prolog which domains the arguments of that predicate belong to.
Visual Prolog comes with a wealth of built-in predicates. You don't need to declare any of them, just use them.
Syntax of predicates declaration predicateName(argument_type1,..., argument_typeN)
The argument types are either standard domains or domains that you've declared in the domains section.