Complex systems can be characterized by classes of equivalency of their elements defined according to system specific rules. We propose a generalized preferential attachment model to describe the class size distribution. The model postulates preferential growth of the existing classes and the...

The paper develops a model of proportionate growth to describe the dynamics of the network of international trade flows. We show that a large number of the empirical regularities characterizing international trade - such as the fraction of zero trade flows across pairs of countries, the positive...

We study size and growth distributions of products and business firms in the context of a given industry. Firm size growth is analyzed in terms of two basic mechanisms, i.e., the increase of the number of new elementary business units and their size growth. We find a power-law relationship...