@InProceedings{gesctowo08a,
  title =	 "Alternative Characterizations for Program Equivalence under
                  Answer-Set Semantics based on Unfounded Sets",
  author =	 "M. Gebser and T. Schaub and H. Tompits and S. Woltran",
  pages =	 "24-41",
  crossref =	 "foiks08"
}
@Proceedings{foiks08,
  title =	 "Proceedings of the Fifth International Symposium on
                  Foundations of Information and Knowledge Systems (FoIKS'08)",
  booktitle =	 "Proceedings of the Fifth International Symposium on
                  Foundations of Information and Knowledge Systems (FoIKS'08)",
  editor =	 "S. Hartmann and G. Kern-Isberner",
  volume =	 4932,
  series =	 "Lecture Notes in Computer Science",
  publisher =	 "Springer-Verlag",
  year =	 2008
}