The Mathematics of the Streets: Modeling Protests Through the Lens of Casual Groups

• Grant number: 25/06044-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: July 31, 2026
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: José Fernando Fontanari
• Grantee: Bianca Yumi Simote Ishikawa
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Street protests, such as Black Lives Matter in the US and the Yellow Vest Movement in France, are a growing and complex phenomenon with significant social and political impact, as evidenced by the Arab Spring. The goal of studying street protests is to understand the temporal dynamics of the number of participants, the geographic spread of the disturbance, and the triggers of collective action, with the prospect of eventually being able to influence the occurrence and impact of these events. The relevant factor to quantify them is the number of participants. While there are several mathematical formulations to describe street protests, such as epidemiological and reaction-diffusion models, in this project we will focus on threshold models. In this context, threshold is defined as the number or proportion of other individuals who must join the protest before a given individual does so. In particular, we will apply a novel mathematical/computational approach to the study of street protest dynamics, inspired by the dynamics of casual groups. This approach incorporates the diversity in individual motivations (thresholds) to join a temporary group or demonstration. (AU)