14. The computer-implemented system of claim 12 , wherein each edge provides a visual representation of a strength of a link between two nodes based on a number of co-occurrences between two individual issues represented by the two nodes.
14. The computer-implemented system of claim 12 , wherein each edge provides a visual representation of a strength of a link between two nodes based on a number of co-occurrences between two individual issues represented by the two nodes. 15. The computer-implemented system of claim 14 , wherein the visual representation comprises a weighted line representing the edge.