From MIT’s Technology Review:
Luciano da Fontoura Costa at the University of Sao Paulo in Brazil and few pals created a computer model of the street and underground networks in London and Paris. The networks of Paris and London had 11699 nodes and 6885 nodes, respectively.
They then let loose ant-like agents to crawl the city streets in self-avoiding random walks and watched to see where they ended up. The researchers simulated a total of 10,000 walks for each node in each network.
They then calculated a “diversity entropy” for each node, a number which captures how easily it is to get from one node to others nearby. The results are shown in the pictures (London on top) in which red areas are more easily accessible.
Why the difference? Rivers and parks, apparently.
(Thanks to Murray Pinchuk.)