# First-order language

### From Conservapedia

A **First-order language** in Zermelo-Fraenkel set theory consists of the following symbols:

- A set of constants, such as
*A*,*B*,*C*, ... - A set of n-ary relations such as
*>(x, y)*. - A set of n-ary functions such as
*+(x, y)*. - An infinite set of variables such as
*x*,*y*,*z*,... - The connectives , .
- quantifiers: , .
- parenthesis: (, ).
- The equality symbol = .

First-order languages are used to describe mathematics in mathematical notation with mathematical formulae.