It's essentially a semantic map or mind map if you will, that according to the Turner Prize guide book shows "both types of music were representative of northern working-class communities and, for the artist, indicated a staunch form of resistance to Thatcher's government in 1980's Britain." The thought that stuck me was that this was a network, with nodes, and a relationships between those nodes as in a social network of friends.
If Deller was right, then he was saying that both types of music, the fight against Thatcher, and Northern communities were a small world, where there would be short journeys between different nodes, however far they were from each other. The check whether it was a small world was by calculating it using the formula for a clustering coefficient.
Watts and Strogatz came up with the idea of the clustering coefficient as a measure of how connected a social network was. It is calculated by dividing the number of links in the network by the maximum possible number of links.The closer to 1 the coefficient is the more interconnected your network, and the smaller a world it is, making it easier for information to flow through its pathways. The maximum number of links can be calculated using the following formula n*(n-1)/2. Where n is the number of nodes in the network.
In History of the World there are 48 nodes, and 80 links between, but there are maximum possible 4,152 links which means the clustering coefficient is 0.070922. This is low. It's not a very connected network at all. But when you take a closer look and see how he has connected Bambaataa to Kraftwerk, and then to melancholy, and then through to The North you understand why we coined the term artistic license