In mathematics, graph theory[1] is the study of graphs, which are mathematical structures used to model relations between objects. Images with imagemaps can be regarded as the objects and the clickable areas create directed connection between the displayed image map and other image maps or specific learning ressource refering to the object displayed on the image. A graph in this context is made up of vertices, nodes, or points that are either

• other image maps showing the linked physical location on the image,
• specific learning resources, refering to the displayed object.

In pgraph theory learning resources as nodes are connected by edges, arcs, or lines during the design of the navigation. The lines are implemented by bi-directional links from one image map to the other and vize-versa. So the graph may be drawn as an undirected graph, meaning that there is no distinction between the two vertices associated with each edge, or its edges may be directed from one vertex to another; see Graph (discrete mathematics) for more detailed definitions and for other variations in the types of graph that are commonly considered. Graphs are one of the prime objects of study in discrete mathematics.