@InProceedings{ComonTreinen:caap94, author = "Hubert Comon and Ralf Treinen", title = "Ordering Constraints on Trees", booktitle = "Colloquium on Trees in Algebra and Programming", editor = "Sophie Tison", pages = "1--14", year = 1994, month = apr, address = "Edinburgh, Scotland", series = {Lecture Notes in Computer Science, vol. 787}, publisher = "Springer-Verlag", }