Tulip provides a system for the management of the hierarchy of graph. The hierarchy subwindow displays the existing instances of subgraph or group with their relationships, the user can change the current view of the graph by clicking directly on the tree. When clicking the right mouse button, a popup menu is displayed, it allows to manage the instances of cluster : remove, clone, create subgraph.
A graph can have several parts of itself : these are stored in the subgraph instances. Some clustering algorithms can made subgraphs. A subgraph have the same object, it is just a part of the graph. It is possible to add properties for the subgraph only or to use the inherited properties.