1. Department of Computer Science, Exeter University , Exeter EX4 4PY , United Kingdom
2. The Alan Turing Institute , London NW12DB , United Kingdom
3. Agglomeration and Social Networks Lendület Research Group, Centre for Economic and Regional Studies, Eötvös Loránd Research Network , Budapest 1097 , Hungary
4. Laboratory for Networks, Technology and Innovation, Corvinus Institute for Advanced Studies, Corvinus University of Budapest , Budapest 1093 , Hungary
5. Department of Economic history, Umeå University , Umeå SE-90187 , Sweden
6. Department of Geography, Umeå University , Umeå SE-90187 , Sweden