In recent years, computational improvements have allowed for more nuanced, data-driven and geographically explicit agent-based simulations. Yet, simulations have struggled to adequately represent the attributes that motivate and drive agents’ actions. Existing population synthesis frameworks usually generate agent profiles limited to socio-demographic attributes. In this paper, we introduce a novel population synthesis framework that integrates a motivational layer into the traditional individual and house-hold socio-demographic layers. Our research extends the profile of agents in synthetic populations to incorporate data on values, ideologies, opinions and vital priorities, all of which play a key role in motivating agents’ behaviour. This motivational layer paves the way for developing data-driven decision-making mechanisms in future agent-based simulations. Our methodology combines microdata and macrodata within different Bayesian network structures or models. This method allows to generate synthetic populations that integrate motivational information while preserving the inherent socio-demographic distributions of the real population.

Social networks contribute to the distribution of social capital, defined as the relationships, norms of trust and reciprocity within a community or society that facilitate cooperation and collective action. Therefore, better positioned members in a social network benefit from faster access to diverse information and higher influence on information dissemination. A variety of methods have been proposed in the literature to measure social capital at an individual level. However, there is a lack of methods to quantify social capital at a group level, which is particularly important when the groups are defined on the grounds of protected attributes. To fill this gap, we propose to measure the social capital of a group of nodes by means of the effective resistance and emphasize the importance of considering the entire network topology. Grounded in spectral graph theory, we introduce three effective resistance-based measures of group social capital, namely group isolation, group diameter and group control, where the groups are defined according to the value of a protected attribute. We denote the social capital disparity among different groups in a network as structural group unfairness, and propose to mitigate it by means of a budgeted edge augmentation heuristic that systematically increases the social capital of the most disadvantaged group. In experiments on real-world networks, we uncover significant levels of structural group unfairness when using gender as the protected attribute, with females being the most disadvantaged group in comparison to males. We also illustrate how our proposed edge augmentation approach is able to not only effectively mitigate the structural group unfairness but also increase the social capital of all groups in the network.

The global rise in homelessness calls for urgent and alternative policy solutions. Non-profits and governmental organizations alert about the many challenges faced by people experiencing homelessness (PEH), which include not only the lack of shelter but also the lack of opportunities for personal development. In this context, the capability approach (CA), which underpins the United Nations Sustainable Development Goals (SDGs), provides a comprehensive framework to assess inequity in terms of real opportunities. This paper explores how the CA can be combined with agent-based modelling and reinforcement learning. The goals are: (1) implementing the CA as a Markov Decision Process (MDP), (2) building on such MDP to develop a rich decision-making model that accounts for more complex motivators of behaviour, such as values and needs, and (3) developing an agent-based simulation framework that allows to assess alternative policies aiming to expand or restore people's capabilities. The framework is developed in a real case study of health inequity and homelessness, working in collaboration with stakeholders, non-profits and domain experts. The ultimate goal of the project is to develop a novel agent-based simulation framework, rooted in the CA, which can be replicated in a diversity of social challenges to assess policies in a non-invasive way.

Bias towards people experiencing homelessness (PEH) is prevalent in online spaces. This project will leverage natural language processing (NLP) and large language models (LLMs) to identify, classify, and measure bias using geolocalized data collected from X (formerly Twitter), Reddit, meeting minutes, and news media across the United States. While public opinion often refers to addictions, criminality, and high levels of welfare spending to justify bias against PEH, we will conduct a comparative study to determine whether racial fractionalization is associated with homelessness bias. The results of the study aim to provide a new path to alleviate homelessness by unveiling the intersectional bias that affects PEH and minority racial groups. During the course of the project, we will deliver a lexicon, compile an annotated database for homelessness and homelessness-racism intersectional (HRI) bias, evaluate LLMs as classifiers of homelessness and HRI bias, develop homelessness and HRI bias metrics, and audit existing LLMs on HRI. In collaboration with non-profits and the city council of South Bend, Indiana, USA, our ultimate goal is to contribute to homelessness alleviation by counteracting social stigma, restoring the dignity and well-being of the persons affected.

Policies that seek to mitigate poverty by acting on equal opportunity have been found to aggravate discrimination against the poor (aporophobia), since individuals are made responsible for not progressing in the social hierarchy. Only a minority of the poor benefit from meritocracy in this era of growing inequality, generating resentment among those who seek to escape their needy situations by trying to climb up the ladder. Through the formulation and development of an agent-based social simulation, this study aims to analyse the role of norms implementing equal opportunity and social solidarity principles as enhancers or mitigators of aporophobia, as well as the threshold of aporophobia that would facilitate the success of poverty-reduction policies. The ultimate goal of the social simulation is to extract insights that could help inform and guide a new generation of policy making for poverty reduction by acting on the discrimination against the poor, in line with the UN “Leave No One Behind” principle. An “aporophobia-meter” will be developed and guidelines will be drafted based on both the simulation results and a review of poverty reduction policies at regional levels.