Lossless Compression of Semi-Ordered Trees

In this paper, authors are interested in the problem of lossless compression of unlabeled semi-ordered trees. Semi-ordered trees are a class of trees that present an order between some sibling while some other sibling are unordered. They offer a wide possibility of applications especially for the representation of plants architecture. Authors show that these trees present remarkable compression properties covering those of ordered and unordered trees. To illustrate this approach, authors apply these notions to a particular class of semi-ordered trees which is the most studied branching structure particularly for a botanical motivation, namely axial trees.