gLPS: A graphical tool for the definition and manipulation of linear problems

The use of suitable tools is one of the cornerstones of every aspect of human activity. In mathematical modeling, graphical representation of complex systems-like circles and arrows to depict states and transitions in Markov chains-has been used for many years. Increased computing power has further stimulated this tendency by offering direct manipulation interfaces that allow users to experiment with the aid of graphical representation of their models. In the area of linear programming, gLPS (graphical Linear Programming System) describes classical linear problems in terms of graphical objects (circles for restrictions, squares for variables, etc.) networked according to specific rules to form a model. The system ensures the consistency of the model, allows for its manipulation and modification through a Macintosh-like interface and activates a solver to compute the solution. The major strength of gLPS resides in the ability to apply the same simple set of components and rules in modeling any kind of linear system (transhipment, product-mix, etc.). gLPS is not only a modeling language, but also an integrated software tool for the construction, modification, documentation and calculation of linear problems.