  Answer Set Programming (ASP) is one of the major declarative programming
paradigms in the area of logic programming and non-monotonic reasoning. Despite
that ASP features a simple syntax and an intuitive semantics, errors are common
during the development of ASP programs. In this paper we propose a novel
debugging approach allowing for interactive localization of bugs in non-ground
programs. The new approach points the user directly to a set of non-ground
rules involved in the bug, which might be refined (up to the point in which the
bug is easily identified) by asking the programmer a sequence of questions on
an expected answer set. The approach has been implemented on top of the ASP
solver WASP. The resulting debugger has been complemented by a user-friendly
graphical interface, and integrated in ASPIDE, a rich IDE for answer set
programs. In addition, an empirical analysis shows that the new debugger is not
affected by the grounding blowup limiting the application of previous
approaches based on meta-programming. Under consideration in Theory and
Practice of Logic Programming (TPLP).
