Modular Nonmonotonic Logic Programming Revisited

Recently, enabling modularity aspects in Answer Set Programming (ASP) has gained increasing interest to ease the composition of program parts to an overall program. In this paper, the authors focus on modular non-Monotonic Logic Programs (MLP) under the answer set semantics, whose modules may have contextually dependent input provided by other modules. Moreover, (mutually) recursive module calls are allowed. They define a model-theoretic semantics for this extended setting, show that many desired properties of ordinary logic programming generalize to the modular ASP, and determine the computational complexity of the new formalism. They investigate the relationship of modular programs to disjunctive logic programs with well-defined input/output interface (DLP-functions) and show that they can be embedded into MLPs.