Ricard V. Sol

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The analysis of some species-rich, well-defined food webs shows that they display the so-called small world behavior shared by a number of disparate complex systems. The three systems analysed (Ythan estuary web, Silwood web and the Little Rock lake web) have different levels of taxonomic resolution, but all of them involve high clustering and short path(More)
In a recent study, Ohira and Sawatari presented a simple model of computer network tra c dynamics. These authors showed that a phase transition point is present separating the low-tra c phase with no congestion from the congestion phase as the packet creation rate increases. We further investigated this model by relaxing the network topology using a random(More)
A new model ecosystem of many interacting species is introduced in which the species are connected through a random matrix with a given connectivity. The model is studied both analytically and by numerical simulations. A probability distribution derived from the model is in good agreement with simulations and eld data. It is also shown that the(More)
Jordi Delgado 1,2,3 and Ricard V. Solé 2,3 Departament de Llenguatges i Sistemes Informatics, Universitat Politecnica de Catalunya, Pau Gargallo 5, 08028 Barcelona, Spain Complex Systems Research Group, Departament de Fı́sica i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Sor Eulàlia d’Anzizu s/n, Campus Nord, Mòdul B4, 08034 Barcelona, Spain(More)
A new order parameter approximation to Random Boolean Networks RBN is introduced based on the concept of Boolean derivative A statistical argu ment involving an annealed approximation is used allowing to measure the order parameter in terms of the statistical properties of a random matrix Using the same formalism a Lyapunov exponent is calculated allowing(More)
We describe a method to discriminate between ordered and turbulent behavior in a general class of collective systems Ž . known as Globally Coupled Maps GCM . Our method is able to discover an unknown small ordered region inside the turbulent phase of GCM parameter space. The computational nature of the method is the main novelty of our approach; it is(More)
In a recent paper, we analysed the dynamics of tra%c /ow in a simple, square lattice architecture. It was shown that a phase transition takes place between a free and a congested phase. The transition point was shown to exhibit optimal information transfer and wide /uctuations in time, with scale-free properties. In this paper, we further extend our(More)