An interesting layout strategy which the author calls horizon tree
is displayed in Fig. 4 d).
This strategy displays a spanning tree, too. In contrast to the current technique, WebMap should automatically decide which nodes to condense and which nodes to expand.
The idea is to place the current node (the one representing the currently displayed WWW page) near the center of the navigation window. WebMap should display every node whose distance (number of edges in shortest path between the two nodes) is smaller or equal to the user defined path length H (the horizon). This should apply independantly of the edge directions (in or out). As a consequence the semantics of node condensing has to be extended to make condensing of ancestors possible.
The effect of this strategy will be, that every node known to WebMap will automatically be displayed if it ``lies between the horizon and the current node''. This circle of visible nodes will wander through the web as the current node does, so a user will always see its closer environment.