Current answer set solvers work on variable-free programs. Hence, a grounder is needed that, given an input program with first-order variables, computes an equivalent ground (variable-free) program. gringo is such a grounder. Its output can be processed further with clasp, claspfolio, or clingcon.

clingo combines both gringo and clasp into a monolithic system. This way it offers more control over the grounding and solving process than gringo and clasp can offer individually - e.g., incremental grounding and solving.

Both clingo and gringo are released together in one package.

Attention! The languages of clingo 3 and 4 are not fully compatible because clingo 4 adheres to the recent ASP language standard. For processing legacy encodings, we recommend downloading the latest version of clingo 3 in addition to clingo 4. The language did not change in version 5 but there were many API changes.