  The paper presents an enhancement of xASP, a system that generates
explanation graphs for Answer Set Programming (ASP). Different from xASP, the
new system, xASP2, supports different clingo constructs like the choice rules,
the constraints, and the aggregates such as #sum, #min. This work formalizes
and presents an explainable artificial intelligence system for a broad fragment
of ASP, capable of shrinking as much as possible the set of assumptions and
presenting explanations in terms of directed acyclic graphs.
