### 3.7.197. Reified constraint

The reified version $\mathrm{𝐶𝑅}$ of a given constraint $C$, where $\mathrm{𝐶𝑅}$ has as arguments all arguments of $C$ plus one extra 0-1 variable. This 0-1 variable is set to 1 when constraint $C$ holds, and 0 otherwise. Note that constraint $\mathrm{𝐶𝑅}$ inherits from all restrictions of constraint $C$ (i.e., incorrect parameters for constraint $C$ are also incorrect for constraint $\mathrm{𝐶𝑅}$). Within the context of linear programming the extra 0-1 variable is often called an indicator variable.