expression that combined with one or more subjects forms a
The given definition follows the usage of "predicate" in
way of forming predicates is to take a statement and replace one or more
subject terms - normally terms that are like common or proper names - by
variables or placeholders. An example is "x1 loves x2" or "_ loves _"
from "Romeo loves Juliet".
The number of variables or placeholders in a predicate is called its
arity or adity. Thus "x1 loves x2" is a two-place or
"x1 is a man" is a one-place or unary predicate; and "x1 is between x2
and x3" is a three-place or triadic predicate.
In logic, predicates with two or more places stand for