Publications

Coexistence of balance and hierarchies: An ego perspective to explain empirical networks

• Piotr J Górski , Adam Sulik , Georges Andres , Giacomo Vaccario , Janusz A Hołyst
• Cooperation and opinion dynamics , Data driven models , Agent based models

How do people change positive and negative relations in social networks? Two conflicting mechanisms, balance and status hierarchies, coexist and influence each other. The mechanisms are integrated into an agent-based model where individuals aim to resolve inconsistencies with balance and status. By fitting the model to real-world networks, one can successfully replicate observed patterns in social networks. The study suggests that social configurations may be fragile and vulnerable to disruptions.

The quest for an unbiased scientific impact indicator remains open

• Giacomo Vaccario , Shuqi Xu , Manuel S Mariani , Matúš Medo
• Science of science

A study published in the journal PNAS questioned the unbiasedness of a scientific impact indicator called ̂c10, which was previously thought to be fair. The analysis shows that ̂c10 exhibits a strong age bias, meaning it favors older papers over newer ones. This bias is due to ̂c10's tendency to rank older papers higher than younger ones. The study suggests that this bias could be a problem for scientists who rely on ̂c10 to evaluate the impact of their research. Furthermore, the study found that raw citation count c outperforms ̂c10 in identifying groundbreaking research, because it is not controlled for temporal distribution. This calls into question the fairness of ̂c10 and highlights the need for more research into algorithmic bias and fairness in scientometrics. The authors of the study suggest that developing unbiased indicators of scientific impact remains a pressing question in the scientometrics and science of science communities.

Efficiency and resilience: Key drivers of distribution network growth

• Ambra Amico , Giacomo Vaccario , Frank Schweitzer
• Pharmaceuticals , Economic networks , Resilience , Data driven models , Agent based models , Supply chain

Distribution networks, which supply goods from manufacturers to final buyers, are crucial for a functioning economy. A network model is proposed to describe the emergence and growth of these networks. The model considers two firm-level practices: centralization and multi-sourcing. Centralization enhances network efficiency by using short distribution paths, while multi-sourcing fosters resilience by providing multiple distribution paths. The model was validated using data on drug shipments in the US, and it successfully replicates several structural features of the empirical networks, including their out-degree and path length distributions, as well as their resilience and efficiency properties. The findings suggest that the proposed firm-level practices effectively capture the network growth process that leads to the observed structures.

Adapting to disruptions: Managing supply chain resilience through product rerouting

• Ambra Amico , Luca Verginer , Giona Casiraghi , Giacomo Vaccario , Frank Schweitzer
• Pharmaceuticals , Economic networks , Resilience , Supply chain

Reconstructing signed relations from interaction data

• Georges Andres , Giona Casiraghi , Giacomo Vaccario , Frank Schweitzer
• Signed relations , Network theory , Data science

This study presents a statistical network method to infer weighted signed relations from interaction data. The method, called the Φ-method, assumes that a statistical over-representation of interactions signals a positive relation and an under-representation signals a negative relation. TheΦ-method was tested on four classical interaction datasets and showed promising results in predicting reported relations and reconstructing the underlying relational networks of the communities.

The Robotic Herd: Using Human-Bot Interactions to Explore Irrational Herding

• Luca Verginer , Giacomo Vaccario , Piero Ronzani
• Cooperation and opinion dynamics , Game theory

A study of 1,997 participants playing a minority game with bots found that 30% followed the majority, despite theoretical expectations of no herding. The study explored how humans interact with automated entities and how their behavior changes when they are aware of interacting with bots. Herding behavior persisted even when participants were aware of interacting with automated entities.

Modeling the impact of environmental consciousness on the supply-demand relationship between firms and customers

• Tianyuan Wang , Giacomo Vaccario , Frank Schweitzer
• Signed relations , Economic networks , Network theory

The study models the impact of environmental consciousness on the supply-demand relationship between firms and customers. Environmental consciousness can lead to supply-demand deficits, but customers forming unconditional supply links and firms improving their environmental-friendly production can mitigate these deficits. The results show that this approach can inform policies to reduce both supply-demand deficits and environmental pollution.

Fragmentation from group interactions: A higher-order adaptive voter model

• Nikos Papanikolaou , Renaud Lambiotte , Giacomo Vaccario
• Network theory , Cooperation and opinion dynamics

The adaptive voter model is extended to hypergraphs to study group interactions. The model reveals new phenomena, such as the formation of bands in magnetization and the lack of an equilibrium state. The results indicate that fragmentation decreases with the threshold parameter gamma and initial mean degree. The model provides an analytic explanation for the bands and their discontinuity when the hypergraphs are sparse. The simulations show that the system can split into two components with opposite opinions.

Modeling social resilience: Questions, answers, open problems

• Frank Schweitzer , Georges Andres , Giona Casiraghi , Christoph Gote , Ramona Roller , Ingo Scholtes , Giacomo Vaccario , Christian Zingg
• Resilience , System thinking

A four-step framework is developed to quantify social resilience in highly volatile organizations. The framework combines agent-based and network models to assess robustness and adaptivity. Instantaneous monitoring is possible using longitudinal data, shifting attention from micro configurations to macro-properties of social networks.

When standard network measures fail to rank journals: A theoretical and empirical analysis

• Giacomo Vaccario , Luca Verginer
• Science of science , Network theory , Data science