In this case, variables ranges over real numbers and terms.
For example, consider the constraint where the variables range over the domain 1 to 3.
Using this method, variables range over domains rather than over relations.
For example, in Zermelo-Fraenkel set theory, variables range over all sets.
That is, all variables range over the natural numbers and not sets thereof, a fact even stronger than their being arithmetical.
Quantified variables range over only one type; hence the underlying logic is first-order logic.
An information source is a sequence of random variables ranging over a finite alphabet Γ, having a stationary distribution.
Tarski did so by positing a universe of points, with lower case letters denoting variables ranging over that universe.
Mathematical reasoning requires variables ranging over some universe of discourse, so that we can reason about generalities rather than merely about particulars.
Theta Circini is a B-class irregular variable, ranging from magnitude 5.0 to 5.4.