Guido Caldarelli
Universita' di Roma I
The fractal properties of Internet
Autori: G. Caldarelli, R. Marchetti, L. Pietronero
Networks and web are present in many aspects of everyday life, from the
watershed where the rivers water is collected, to the veins and lymphatic
channels that distribute blood and nutrition in animals and plants, to
the telephone or electricity or internet webs that transport in our houses
the services we need. In all these cases, the network properties should
be such to optimize the number of points connected with respect to the
length of the web and with respect to the amount of material or information
transferred. In this paper we provide a measure of the Internet web, by
using the theoretical framework introduced for the statistical mechanics
of the river networks. The connections between users and providers that
link all the world web are studied and modeled as branches of a world spanning
tree. Here we show that the Internet web, from a user's perspective, manifests
robust scaling properties of the type$ P(n) \propto n^{-t}$ where n is
the size of the basin connected to a given point, P represents the density
of probability of finding n points uphill and $t\simeq 1.9$ is a characteristic
universal exponent.