Improving the representation of infinite trees to deal with sets of trees

Abstract. In order to deal efficiently with infinite regular trees (or other pointed graph structures), we give new algorithms to store such structures. The trees are stored in such a way that their representation is unique and shares as much as possible. This maximal sharing allows substantial memory gain and speed up. For example, equality testing becomes constant time. The algorithms are incremental, and as such allow good reactive behavior. These new algorithms are then applied to the representation of sets of trees. The expressive power of this new representation is exactly what is needed by set-based analysis.