Debugging ASP Programs by Means of ASP

Abstract

Abstract. Answer-set programming (ASP) has become an important paradigm for declarative problem solving in recent years. However, to further improve the usability of answer-set programs, the development of software-engineering tools is vital. In particular, the area of debugging provides a challenge in both theoretical and practical terms. This is due to the purely declarative nature of ASP that, on the one hand, calls for solver-independent methodologies and, on the other hand, does not directly apply to tracing techniques. In this paper, we propose a novel methodology, which rests within ASP itself, to sort out errors on the conceptual level. Our method makes use of tagging, where the program to be analyzed is rewritten using dedicated control atoms. This provides a flexible way to specify different types of debugging requests and a first step towards a dedicated (meta level) debugging language.

Stepping through an Answer-Set Program

“…Then, the user assigns constants to the variables occurring in r. Both steps can be assisted by filtering techniques. A stepping system can provide the user with information which non-ground rules in Π have instances that are active under Int[S] but not contained in S. This can be done using ASP itself using meta-programming and tagging transformations [5,2].…”

“…Using the filtering techniques for variable substitutions, the user can be guided to a concrete active instance of c 2 , viz. to c 2 = ← empty(1, 2), empty(2, 2), empty(1, 2), empty (2,3). It is obvious that the cells (1, 2),(2, 2), (1,2), and (2, 3) do not form a valid 2 × 2 block and hence the wrong term in c 2 can be easily detected.…”

“…to c 2 = ← empty(1, 2), empty(2, 2), empty(1, 2), empty (2,3). It is obvious that the cells (1, 2),(2, 2), (1,2), and (2, 3) do not form a valid 2 × 2 block and hence the wrong term in c 2 can be easily detected. A correct program Π 4 is obtained from Π 3 by changing c 2 .…”

“…A general problem in debugging is to restrict the amount of debugging information that is presented to the user in a sensible way. In the stepping method, this is realised by focussing on one step at a time, which is in contrast to other debugging methods for ASP [2][3][4][5], where the program to be debugged is analysed as a whole. Moreover, due to the interactivity of the approach, the programmer can easily guide the search for bugs following his or her intuitions about which part of the program is likely to be the source of error.…”

VIDEAS: A Development Tool for Answer-Set Programs Based on Model-Driven Engineering Technology

“…However, practice has shown that the development of answer-set programs is not always straightforward and that programs are, as all human-made artifacts, prone to errors. In fact, debugging in ASP is currently a quite active research field [1][2][3][4][5][6][7][8][9].…”