The arity of a CycL relation (predicate or function) is the number of arguments it takes. It is declared in the KB with the predicate #$arity.
- Instances of
#$UnaryPredicateand#$UnaryFunctiontake just 1 argument. - Instances of
#$BinaryPredicateand#$BinaryFunctiontake 2 arguments. - …and so on for the other instances of
#$PredicateTypeByArity
Each instance of #$VariableArityRelation is a relation that can take a variable number of arguments.