Il dilemma Cooperazione vs Competizione in applicazioni economiche e ecologiche

Cooperation and competition are two opposing manifestations that an entity of any nature can present when it interacts with another one. These two behavioral tendencies can manifest themselves in various subjects and at different levels: cells in our body, individuals in a social group, companies in the market, nations in the world, animals in an ecosystem and so on. One can almost say that every aspect of our life is permeated by this eternal conflict between cooperation and competition. The topic is therefore of crucial importance: understanding the basic concepts of cooperation and competition is fundamental to dissecting the dynamics of all these phenomena. Without claiming to explain the deep mechanisms underlying the phenomena of cooperation and competition, this thesis focuses on economic and ecological applications. The first chapter is devoted to the discussion of mathematical models for the study of cooperation and competition, from Game Theory to dynamic systems models. The two systems analyzed are very different in nature, but their study still falls within the framework of complex systems, to which is dedicated the second chapter with an in-depth analysis of trophic networks. In the first study the issue of tax evasion is addressed. This is an age-old phenomenon that clearly is related to cooperation and competition. Think about a selfish citizen who uses public goods and services without properly contributing to the related costs. The main effect of this behavior is a severe damage to the socio-economical environment that deprives governments of their fiscal resources and plays an important role in reducing well-being of societies. In the third chapter an agent-based model of a simple economic system is presented. The personal satisfaction gained from public services and the perceived opinion of neighbors are shown to drive the individual decision on tax compliance. Results of simulations, consistent with existing literature on the topic, suggest a peculiar approach to face the plague of tax evasion. In the second study, exposed in the fourth chapter, using data collected in the Netherlands, ecosystems of soil invertebrates are investigated through the knowledge of their characteristic trophic web. The first part focuses on a single ecosystem and a model is created whose dynamics is dictated by an extension of the Lotka-Volterra equations. In particular, the Lotka-Volterra model is combined with the logistic equation in order to take into account intra-specific and inter-specific competition. The consequences of artificial perturbations induced to the system are analyzed through simulations. Results are interesting because they give an idea of the vulnerability of soil ecosystems if subjected to the use of herbicides or pesticides typical of intensive agriculture. In the second part, the same model is applied to other two ecosystems different from the first for the type of human activity to which they are subject. Their structure and their response to external disturbances are compared. The final analysis on their robustness clearly shows that the ecosystem less subject to anthropogenic disturbances has a structure that makes it more resistant against perturbations. In this second study, competitiveness is not only found at the level of the trophic web (in the search for resources and in the fight for survival between prey and predator), but, at a different level, comes into play competitiveness between ecosystem organisms and human action that tends to contaminate natural habitats. Human cooperation in this case would consist of seeking eco-sustainable solutions rather than intensive farming methods.