@INPROCEEDINGS{mp04A,
  author = {A. Montanari and G. Puppis},
  title = {Decidability of the Theory of the Totally Unbounded $\omega$-Layered Structure},
  booktitle = {Proceedings of the 11th International Symposium on Temporal Representation and Reasoning (TIME)},
  year = {2004},
  pages = {156-160}
}