Davide Nunes

Context Switching versus Context Permeability in Multiple Social Networks

In social life, actors engage simultaneously in several relations with each other. The complex network of social links in which agents are engaged is fundamental for any realistic simulation of social life. Moreover, not only the existence of multiple-modality paths between agents in a simulation, but also the knowledge that those agents have about the quality and specificity of those links are relevant for the decisions the agents make and the consequences they have both at an individual and at a collective level. Each actor has a context in each of the relations that are represented as support of a simulation. We build on previous work about permeability between those contexts to study the novel notion of context switching. By switching contexts, individuals carry with them their whole set of personal characteristics to a different relation, while abandoning the previous one. When returning to the original context, all previous links are resumed. We apply these notions to a simple game: the consensus game, in which agents try to collectively achieve an arbitrary consensus through simple locally informed peer-to-peer interactions. We compare the results for context switching with results from simulating the simple game and the game with context permeability.

Dynamics of Relative Agreement in Multiple Social Contexts

In real world scenarios, the formation of consensus is an self-organisation process by which actors have to make a joint assessment about a target subject being it a decision making problem or the formation of a collective opinion. In social simulation, models of opinion dynamics tackle the opinion formation phenomena. These models try to make an assessment, for instance, of the ideal conditions that lead an interacting group of agents to opinion consensus, polarisation or fragmentation. In this paper, we investigate the role of social relation structure in opinion dynamics using an interaction model of relative agreement. We present an agent-based model that defines social relations as multiple concomitant social networks and apply our model to an opinion dynamics model with bounded confidence. We discuss the influence of complex social network topologies where actors interact in multiple relations simultaneously. The paper builds on previous work about social space design with multiple contexts and context switching, to determine the influence of such complex social structures in a process such as opinion formation.

Parallel Execution of Social Simulation Models in a Grid Environment

The exploration of agent-based social simulation models with a systematic analysis over its parameter space leads to a common problem. It takes too much time to get enough results for a significant analysis of the data generated by the simulation runs over those models. In this paper we show how one can minimise this problem by using grid computing. That is, constructing a social simulation model, designing an experiment and distributing the experiment over a computer grid, running a social simulation model with different parameter combinations in parallel. We supply a working example using the MASON framework and the JPPF framework.

Modelling structured societies

The structure of social relations is fundamental for the construction of plausible simulation scenarios. It shapes the way actors interact and create their identity within overlapping social contexts. Each actor interacts in multiple contexts within different types of social relations that constitute their social space. In this article, we present an approach to model structured agent societies with multiple coexisting social networks. We study the notion of context permeability, using a game in which agents try to achieve global consensus. We design and analyse two different models of permeability. In the first model, agents interact concurrently in multiple social networks. In the second, we introduce a context switching mechanism which adds a dynamic temporal component to agent interaction in the model. Agents switch between the different networks spending more or less time in each one. We compare these models and analyse the influence of different social networks regarding the speed of convergence to consensus. We conduct a series of experiments that show the impact of different configurations for coexisting social networks. This approach unveils both the limitations of the current modelling approaches and possible research directions for complex social space simulations.

Public and Private Partner Selection in Battle of Sexes

In this paper the authors investigate what factors can promote population diversity. They compare different partner selection models and strategy mobility on the Battle of Sexes game. This is a game with a coordination dilemma where players must decide which event to attend given that each one has its preferred event but they prefer going together. They investigate two types of partner selection: one based in private information and another based on public information, which is based on an opinion model. The authors analyze two variants of the opinion model. Experimental analysis shows that partner selection plays a minor role of favoring population diversity. One of the most important factors is strategy mobility either implicitly through mutation or explicitly when an offspring is placed in a different location.

Achieving Consensus with Segregation in Multiple Social Contexts

In social simulation, not only are the structures of the social relations fundamental for the construction of plausible scenarios, but also the interaction processes are shaped by these structures. Each actor interacts in multiple social contexts located within multiple social relations that constitute his social space. We build on previous work about context switching to study the notion of context segregation. The agents not only switch between social contexts, carrying with them their unique social identities, but also choose the contexts according to personal reasons. We apply the notion of context segregation to a simple game of consensus in which agents try to collectively achieve an essentially arbitrary consensus. We make a first analysis of our set of experiments towards understanding the influence of the segregation mechanism in the speed of convergence to global consensus and compare the results with those of the context switching model.