A higher-order predicate is a predicate that takes one or more other predicates as arguments. Relationships between predicates can be stated using logical connectives. Semantic dependencies are understood in terms of predicates and their arguments. Iterative algorithms can be implemented by means of recursive predicates. More complex functional primitives may be defined by boolean combinations of simpler predicates. Prototypically, verbs are used to construct predicates, while nouns are used as arguments of predicates. Relational operators can be seen as special cases of logical predicates. This prompts the omnipredicative interpretation, which posits that all nouns are also predicates. Note that categorical syllogisms have elements traditionally called middles, predicates, and subjects. The causative mu- is used to increase the valence of intransitive predicates. For locative predicates, the copula is . The general copula is ; it is used to convey identity with nominal predicates. NaN. The other standard comparison predicates are all signaling if they receive a NaN operand. Horn clause programs can only represent state change by the change in arguments to predicates. He distinguishes between qualitative and locational predicates.