You should now be familiar with the use of the variable domain functions @BIN and @GIN, and how they are used to introduce integer variables into a model. This section has shown how integer variables bring a whole new dimension of power to the mathematical modeler. Given that we have only briefly delved into the topic of modeling with integer variables, the user that would like to become more familiar with the many practical applications of integer programming and their formulations can refer to Schrage (2006), or Winston (1995).