Daniele Ietri

Inter-similarity between coupled networks

Recent studies have shown that a system composed of several randomly interdependent networks is extremely vulnerable to random failure. However, real interdependent networks are usually not randomly interdependent, rather pairs of dependent nodes are coupled according to some regularity which we coin inter-similarity. For example, we study a system composed of an interdependent world wide port network and a world wide airport network and show that well-connected ports tend to couple with well-connected airports. We introduce two quantities for measuring the level of inter-similarity between networks: i) the inter degree-degree correlation (IDDC); ii) the inter-clustering coefficient (ICC). We then show both by simulation models and by analyzing the port-airport system that as the networks become more inter-similar the system becomes significantly more robust to random failure.

Urban competitiveness : theory and practice

Daniele Ietri is Lecturer in the Faculty of Political Sciences at the University of Turin, Italy Peter Kresl is Charles P. Vaughan Chair in Economics at Bucknell University, USA

The Aging Population and the Competitiveness of Cities

While much of the current literature on the economic consequences of an aging population focuses on the negative aspects, this enlightening book argues that seniors can bring significant benefits – such as vitality and competitiveness – to an urban economy.

Innovation creation and diffusion in a social network: an agent based approach

Market is not only the result of the behaviour of agents, as we can find other forms of contact and communication. Many of them are determined by proximity conditions in some kind of space: in this paper we pay a particular attention to relational space, that is the space determined by the relationships between individuals. The paper starts from a brief account on theoretical and empirical literature on social networks. Social networks represent people and their relationships as networks, in which individuals are nodes and the relationships between them are ties. In particular, graph theory is used in literature in order to demonstrate some properties of social networks summarised in the concept of Small Worlds. The concept may be used to explain how some phenomena involving relations among agents have effects on multiple different geographical scales, involving both the local and the global scale. The empirical section of the paper is introduced by a brief summary of simulation techniques in social science and economics as a way to investigate complexity. The model investigates the dynamics of a population of firms (potential innovators) and consumers interacting in a space defined as a social network. Consumers are represented in the model in order to create a competitive environment pushing enterprises into innovative process (we refer to Schumpeter’s definition): from interaction between consumers and firms innovation emerges as a relational good.

Creating Cities/Building Cities

For the past 150 years, architecture has been a significant tool in the hands of city planners and leaders. In Creating Cities/Building Cities, Peter Karl Kresl and Daniele Ietri illustrate how these planners and leaders have utilized architecture to achieve a variety of aims, influencing the situation, perception and competitiveness of their cities.