Algebraic hierarchical graph transformation

AbstractThis paper presents a framework for constructing hierarchical (hyper)graphs, using one of the well-known categories of traditional flat (hyper)graphs as a base. Hierarchical graphs are obtained from flat graphs by adding a parent assigning function to them. Any graph atom (vertex or edge) can be assigned as a child of any other atom. Hierarchical graphs are more expressive than flat graphs, yet similar enough that the double-pushout approach to graph transformation can be extended to them