Dr. Giona Casiraghi
I work on two tighly connected topics. How to define and quantify resilience, in complex systems in general and in social organisations in particular. How to model complex systems from the data, to perform a data-driven study of their properties.
Resilience of Social Organisations
We aim at an understanding of how different online social organisations withstand and recover from internal and external shocks, and how such a resilience can be improved. To do, so we investigate how different resilience metrics can be computed from data. Our research is deeply rooted in data science and the data-driven modelling of complex systems. We use and develop new methodologies from network science, multivariate statistics, machine learning, and statistical physics.
Statistical Models for Network Data
To allow the study of complex dynamical systems such as social organisations, we need inferential models aimed at temporal and multi-edge network data. I am interested in the development of quantitative methods for the analysis of repeated interactions arising in social, economical, and political networks. A second line of research I follow focuses on modelling and understanding temporal correlation observed in temporal network data, such as distribution networks and communication networks.
Part of my work revolves around the generalised hypergeometric ensemble of random graphs, gHypEG for short. In its simplest form, gHypEG provides a model preserving vertices’ activities. Doing so, it maps the standard configuration model to an urn problem. Pairs of nodes are like balls in an urn. The more frequent are specific balls, the more likely are edges to be sampled. In its general form, edge probabilities are again defined by balls’ frequencies, but also by independent edge propensities estimated from data. The higher the propensity, the larger the ball, the easier it is to sample the edge. The main applications of gHypEG, are towards the inference of significant relations from observed interactions, and the analysis of complex networks by means of network regressions.
The R package ghypernet provides an Open Source implementation for R of a set of functions to work with gHypEG models.
GHYPERNET Tutorials and Material
The following links contain a collection of tutorials and material about the ghypernet R package.
Tutorial to network regression models: https://sg.ethz.ch/nrm-tutorial/
Companion git repository for the 2019 EUSN Workshop in Zurich: https://github.com/sg-dev/EUSN2019_r-ghypernet
Repository for the EuroCSS Tutorial “Introduction to Multi-edge Network Inference in R Using the Ghypernet-package”: https://github.com/sg-dev/EuroCSS2019_r-ghypernet
GitHub repository for ghypernet: https://github.com/gi0na/r-ghypernet
Manual and Vignettes of the R package: https://ghyper.net
Giona's most recent publications
Spillover of Antisocial Behavior from Fringe Platforms: The Unintended Consequences of Community Banning
Proceedings of the International AAAI Conference on Web and Social Media - 2023
Adapting to Disruptions: Flexibility as a Pillar of Supply Chain Resilience
arXiv - 2023
Understanding Online Migration Decisions Following the Banning of Radical Communities
Proceedings of the 15th ACM Web Science Conference 2023 - 2023
Locating Community Smells in Software Development Processes Using Higher-Order Network Centralities
Social Network Analysis and Mining - 2023
Modeling social resilience: Questions, answers, open problems
Advances in Complex Systems - 2022
Struggling with change: The fragile resilience of collectives
Perspectives on Psychological Science - 2022
Reconstructing signed relations from interaction data
arXiv - 2022
Comparing Online and Offline Political Support
Swiss Political Science Review - 2022
The downside of heterogeneity: How established relations counteract systemic adaptivity in tasks assignments
Entropy, 23(12), 1677 - 2021
Configuration models as an urn problem
Scientific Reports 11, 13416 - 2021
The likelihood-ratio test for multi-edge network models
J. Phys. Complex. 2 035012 - 2021
Fragile, Yet Resilient: Adaptive Decline in a Collaboration Network of Firms
Frontiers in Applied Mathematics and Statistics - 2021
Predicting Sequences of Traversed Nodes in Graphs using Network Models with Multiple Higher Orders
arXiv preprint arXiv:2007.06662 - 2020
Intervention scenarios to enhance knowledge transfer in a network of firms
Frontiers in Physics - 2020
Improving the robustness of online social networks: A simulation approach of network interventions
Frontiers in Robotics and AI - 2020