A graph is a structure consisting of nodes and edges. An edge has a source and destination node and "connects" them together.

The line graph is a graph created by swapping nodes and edges. Each edge of the original graph is a node in the corresponding line graph. Two nodes in the line graph are adjacent, i.e. connected to each other, exactly when the corresponding edges in the original graph have a common node.

The view is divided into three sections:

In "Nodes", new nodes can be created and edited in the graph.

In "Edges", new edges can be created and edited in the graph.

The last area contains a representation of the (directed) line graph for the different tree alike components in TopLogic.

Suppose the user has created 5 nodes for the graph and the following edges:

Then the (directed) line graph starting from ROOT (edge from Node1 to Node2) is displayed in the following image:

The children of ROOT are all the edges that have the destination of ROOT in their source. Since ROOT has Node2 as its target, the children of ROOT are exactly Edge1 and Edge3, since they also have Node2 as their source. Using this tree, it is easy to read the different paths in the original graph. For example, Node1 (source of ROOT) -> Node2 (destination of Root or source of Edge1) -> Node3 (destination of Edge1 or source of Edge2) -> Node4 (destination of Edge2), i.e. a path from Node1 to Node4 via the edges ROOT, Edge1 and Edge2.

To model more complex issues, the nodes have a color. The (directed) line graph of nodes of the same color is the line graph already described in that only paths over nodes of the same color are represented. If an edge has nodes for the source and the destination with different colors, then the edge is not part of this line graph.

The view demonstrates more complex tree updates for trees that are not built via a direct association of parents to child nodes, but via calculated relations. For this purpose, an line graph model is created in which changes in node objects (setting the color), which are not even represented in the tree, result in changes to the tree structure.