title: The anatomy of urban social networks and its implications in the searchability problem.
abstract: The appearance of large geolocated communication datasets has recently increased our understanding of how social networks relate to their physical space. However, many recurrently reported properties, such as the spatial clustering of network communities, have not yet been systematically tested at different scales. In this work we analyze the social network structure of over 25 million phone users from three countries at three different scales: country, provinces and cities. We consistently find that this last urban scenario presents significant differences to common knowledge about social networks. First, the emergence of a giant component in the network seems to be controlled by whether or not the network spans over the entire urban border, almost independently of the population or geographic extension of the city. Second, urban communities are much less geographically clustered than expected. These two findings shed new light on the widely-studied searchability in self-organized networks. By exhaustive simulation of decentralized search strategies we conclude that urban networks are searchable not through geographical proximity as their country-wide counterparts, but through an homophily-driven community structure.
authors.affiliation: 1] Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA [2] Depto. Matemática Aplicada a las Tecnologías de la Información y las Comunicaciones (TIC), ETSI Telecomunicación, Universidad Politécnica de Madrid (UPM), Spain [3] Cátedra Orange. Universidad Politécnica de Madrid (UPM), Spain.
authors.forename: C
authors.initials: C
authors.lastname: Herrera-Yagüe
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Schneider
authors.affiliation: Sociology and Economics of Networks and Services department, Orange Labs, Issy les Moulineaux, France.
authors.forename: T
authors.initials: T
authors.lastname: Couronné
authors.affiliation: Sociology and Economics of Networks and Services department, Orange Labs, Issy les Moulineaux, France.
authors.forename: Z
authors.initials: Z
authors.lastname: Smoreda
authors.affiliation: 1] Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA [2] Grupo de Sistemas Complejos, Departamento de Física y Mecánica, ETSI Agrónomos, Universidad Politécnica de Madrid (UPM), Spain.
authors.forename: R M
authors.initials: RM
authors.lastname: Benito
authors.affiliation: 1] Depto. Matemática Aplicada a las Tecnologías de la Información y las Comunicaciones (TIC), ETSI Telecomunicación, Universidad Politécnica de Madrid (UPM), Spain [2] Cátedra Orange. Universidad Politécnica de Madrid (UPM), Spain.
authors.forename: P J
authors.initials: PJ
authors.lastname: Zufiria
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: González