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Valerio Ciotti

 Valerio Ciotti


Tel: +44 (0)20 7882 3921
Location: Mile End, Bancroft Building, Room 4.25h


1st Supervisor: Dr Pietro Panzarasa
2nd Supervisor: Professor Vito Latora

Project Title: 

"Revisiting homophily and tie creation in social networks"

Project Description: 

My research is broadly concerned with the analysis of complex networks, and in particular social networks of interacting individuals, groups, or organisations. A number of network growth mechanisms have been suggested to explain how ties are forged and severed over time. Among these mechanisms, a key role is played by homophily, namely the principle that similarity breeds connection. 

While the social environment may influence individuals’ mental attitudes, and individuals may become similar as a result of their interaction, a substantial body of empirical research has provided evidence in favour of the hypothesis that social interactions between individuals arise precisely as a result of their similarity and convergence on the same ideas, beliefs, interests, and attitudes.

While homophily boasts a long intellectual tradition in the social sciences, organisational ecologists have suggested that similarity can also lead to competition for scarce resources. For instance, competition among organisations using similar strategies, having similar size, and sharing the same market targets tends to be stronger than competition among dissimilar organisations. 

My research project aims to develop a model of network dynamics and tie creation that combines and extends the homophily and ecological arguments to investigate the non-linear effects of increasing degrees of similarity on the probability of tie creation. My approach to research is strongly interdisciplinary, as I integrate sociological and organisational theories with recent advances in the mathematical, statistical, and computatational sciences.

My research interests also include the study of topological properties of multiplex networks, in which the same nodes belong to multiple coevolving layers, and of signed networks, in which links between nodes can have positive (eg, friendship, collaboration) or negative (eg, enmity, competition) connotations.


V. Ciotti, G. Bianconi, A. Capocci, F. Colaiori, and P. Panzarasa (2015). Degree correlations in signed social networks. Physica A: Statistical Mechanics and its Applications 422: 25-39

V. Ciotti, M. Bonaventura, V. Nicosia, P. Panzarasa, V. Latora (2015). Homophily and missing links in citation networks. arXiv: 1511.07643 v1 [physics.soc-ph]

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