Arianna Dal Forno

Original article: Border-collision bifurcations in a model of Braess paradox

In Braess paradox adding an extra resource, and therefore an extra available choice, enriches the complexity of the game from a dynamic perspective. The analysis of the cycles and the bifurcations helps to visualize how this complexity changes, in a quite new way with respect to what is provided by the so far literature. We derive the conditions for the creation and the destruction of periodic cycles, as well as the analytical expressions of the bifurcation conditions, by studying the occurrence of border-collision bifurcations. We are also able to give a proof of the relation between the cost of the new resource and the existence of cycles of any given period, and also of the coexistence of equilibria, adding the path dependence to the problem.

Replicating human interaction in Braess paradox

The Braess Paradox shows how adding a new road to a traffic network may actually increase the total travel time. It has recently found new interest in research. Researchers conducted new experiments with human participants in order to observe the outcomes with an increasing number of people, with private or public monitoring. A small number of papers were devoted to the observation of different behaviors, and intuitively suggested some theoretical hypotheses about the heterogeneity of the participants. Analyzing the data gathered from the observation of an experiment with human participants, and coding artificial behaviors emerged by mean of Grounded Theory, we used ABM simulations to confirm or disprove possible behaviors and composition of the population that was so far suggested only theoretically.

Dynamics of a 2D Piecewise Linear Braess Paradox Model: Effect of the Third Partition

In this work, we investigate the dynamics of a piecewise linear 2D discontinuous map modeling a simple network showing the Braess paradox. This paradox represents an example in which adding a new route to a specific congested transportation network makes all the travelers worse off in terms of their individual travel time. In the particular case in which the modeled network corresponds to a binary choice situation, the map is defined on two partitions and its dynamics has already been described. In the general case corresponding to a ternary choice, a third partition appears leading to significantly more complex bifurcation structures formed by border collision bifurcations of stable cycles with points located in all three partitions. Considering a map taking a constant value on one of the partitions, we provide a first systematic description of possible dynamics for this case.

Network Dynamics when Selecting Work Team Members

When selecting work team members several behavioral components con- cur. In this chapter we summarizes our line of research on this topic; here, we artic- ulate our results and provide suggestions for extending our analysis in order to shed light on the selection of work team members. First, a computational model - to- gether with a theoretical approach and the results of two human experiments where subjects interact in a similar game - allows us to identify some of the most impor- tant determinants. Our results suggest that the occurrence of two factors is crucial: the presence of leaders as aggregators of knowledge and the presence of agents able to expand and improve their higher profit projects. Second, we explicitly assume the presence of formal leaders. By analyzing the results of this modified model, we shed light on the conditions which allow the emergence of effective leaders.

Individual incentives in supervised work groups: from human subject experiments to agent based simulation

We consider a model of work group interaction and introduce an incentive scheme in order to prevent dissatisfaction in subordinates. Several behaviours, which are grounded on observing human subjects when interacting in a similar task, are implemented in artificial agents and simulated. Our results shed light on some aspects of interaction between individuals in complex environment and economic performance, and give insights in terms of observation of the performance measures in organisations.

MODULAR PYRAMIDAL HIERARCHIES AND SOCIAL NORMS. AN AGENT BASED MODEL

AbstractWe provide a model of hierarchical organization where artificial agents with limited individual capacities allocate their efforts in two activities. Different incentives schemes are considered and individual diversity and social norms are approached.

Dynamics in Braess Paradox with Nonimpulsive Commuters

In Braess paradox the addiction of an extra resource creates a social dilemma in which the individual rationality leads to collective irrationality. In the literature, the dynamics has been analyzed when considering impulsive commuters, i.e., those who switch choice regardless of the actual difference between costs. We analyze a dynamical version of the paradox with nonimpulsive commuters, who change road proportionally to the cost difference. When only two roads are available, we provide a rigorous proof of the existence of a unique fixed point showing that it is globally attracting even if locally unstable. When a new road is added the system becomes discontinuous and two-dimensional. We prove that still a unique fixed point exists, and its global attractivity is numerically evidenced, also when the fixed point is locally unstable. Our analysis adds a new insight in the understanding of dynamics in social dilemma.

Chaotic Dynamics in Organization Theory

Modern organizations are increasingly seen as open complex adapitve systems, with fundamental natural nonlinear structures, subject to internal and external forces which may be sources of chaos. The related existing literature focuses mainly on verbal theories where chaos is used as a metaphor. Even if borrowing knowledge brings implicit risks, the usefulness of interdisciplinary knowledge is acknowledged. In this perspective, we show that the chaos metaphor grounded on mathematical models and psychological aspects of human behavior provides helpful insights to describing the complexity of small work groups, that go beyond the metaphor itself.