In
mathematical logic
Mathematical logic is the study of Logic#Formal logic, formal logic within mathematics. Major subareas include model theory, proof theory, set theory, and recursion theory (also known as computability theory). Research in mathematical logic com ...
, a first-order predicate is a
predicate that takes only individual(s) constants or variables as argument(s).
[.] Compare
second-order predicate and
higher-order predicate.
This is not to be confused with a one-place predicate or monad, which is a predicate that takes only one argument. For example, the expression "is a planet" is a one-place predicate, while the expression "is father of" is a two-place predicate.
See also
*
First-order predicate calculus
*
Monadic predicate calculus
References
Predicate logic
Concepts in logic
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