@inproceedings{apinis13,
  author = {Kalmer Apinis and Helmut Seidl and Vesal Vojdani},
  title = {How to combine widening and narrowing for non-monotonic systems of equations},
  booktitle = {Proceedings of the 34th ACM SIGPLAN conference on Programming language design and implementation},
  year = 2013,
  pages = {377--386},
}