Definition:Free Variable/Predicate Logic
< Definition:Free Variable(Redirected from Definition:Free Variable (Predicate Logic))
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Definition
In predicate logic, a free variable is a variable which exists in a WFF only as free occurrences.
Also known as
A free variable is often referred to as an unknown, particularly in mathematical contexts.
In the field of logic, a free variable can also be referred to as a real variable.
However, this can be confused with a variable whose domain is the set of real numbers, so its use on $\mathsf{Pr} \infty \mathsf{fWiki}$ is discouraged.
The name arises in apposition to the name apparent variable, which is another name for bound variable.
Also see
- Definition:Free Occurrence: a somewhat more precise concept, recognising the fact that a variable may appear multiple times in an expression, and not necessarily always of the same category.