ABSTRACT
A network, then, is a graph in the proper meaning of graph theory – a set of nodes and a set of relations, or links, connecting pairs of nodes (Bollobas 1998). STA network nodes are mostly firms, and less frequently other types of organizations such as universities or research centres. Each node is characterized by certain attributes such as size, profitability, age, innovativeness and technological specialization. The typical attributes of pairs of nodes are measures of similarity or dissimilarity in such dimensions. We will often distinguish between three types of nodes: (i) large, incumbent firms; (ii) new, typically small firms and (iii) public research organizations. The distinction matters because the three types of nodes usually play different roles in networks. By analogy, we can also talk of attributes of networks. In the case of STA networks, attributes can refer to structure and performance, including the rate and direction of technological progress.
