# Reified constraint

If a constraint $LaTeX: C$ is reified by a Boolean variable $LaTeX: r$ then $LaTeX: r$ is true only if $LaTeX: C$ holds and false otherwise, i.e. $LaTeX: C \leftrightarrow r$. As an example consider $LaTeX: x = y \leftrightarrow b$ where $LaTeX: x = y$ is a constraint reified by $LaTeX: b$.
Reification is the primary mechanism, for example, in composing a higher level constraint from a logical combination of other constraints: Constraint $LaTeX: A$ could be $LaTeX: (w = 1 \vee z = 17)$ for variables $LaTeX: w,z$.