Problem Solving Using the HEX Family

The HEX formalism has been designed as an extension of answer set programs that offers an abstract interface to access external sources of information and computation, such as the World Wide Web or description logics reasoners. The generic nature makes the extension powerful, which has been exploited in different ways: as an end user problem solving language, as a backend formalism, or as the basis of a richer formalism with possibly increased expressiveness. The increasing spread of HEX is paralleled with the frequently asked questions of what HEX is, and how it can be used for problem solving. In this paper, we aim to answer these questions; we consider different scenarios and provide a methodology for applying HEX from a user perspective. Furthermore, we briefly present a collection of applications based on HEX or derived from it, including sample snippets from associated HEX programs.