Quick tour of Hexaly’s modeler¶

The best way to discover LocalSolver is to use the built-in modeling language. It provides many mathematical operators and facilitates goal programming. The language itself, called LSP (for LocalSolver Programming language) can be both used for programming and modeling: in the same LSP program it is possible to manipulate data structures as in an imperative language and define the optimization model.

As a result, models written in LSP language are really concise and readable. They are structured around 5 predefined functions: input(), model(), param(), display(), output(). These functions, called in this order, induce the flow of the program launched by the LocalSolver executable:

• input: for declaring your data or reading them from files.

• model: for declaring your optimization model.

• param: for parameterizing the local-search solver before running.

• display: for displaying some info in console or in some files during the resolution.

• output: for writing results in console or in some files, once the resolution is finished.

The quick tour of Hexaly’s modeler covers the following main topics: the basics of mathematical modeling, the programming style, and the list of all built-in variables and functions. For more details on the modeling language, see Hexaly Modeler (LSP).

We start this tour by solving a celebrated problem of the operations research literature: the knapsack problem.