(joint work with D. Kontokostas and T. Theodoridis)
Recommendation systems are at the core of Web 2.0 acting like “virtual” salespersons, which collaboratively filter and propose products to consumers of Web stores. This article, investigates the Amazon co-purchase network, which is formed by every recommendation of the top selling products in all product categories. Analysis of motifs and communities has been employed in order to understand the basic patterns of aggregate consumption. Network analysis revealed that Amazon has evolved into a book-based multi-store with strong cross-category connections. In addition, co-purchase links not only manifest complementary consumption, but also switching among competitive products. As expected, top selling products are important in the co-purchase network, acting as hubs, authorities and brokers in consumer preferences. Unexpectedly, it was found that ostensibly competitive products are consumed as complements because of the existence of compatibility and compatible products that facilitate their joint consumption.
M. Vafopoulos, D. Kontokostas and T. Theodoridis (2011), Inter-viewing the Amazon web salespersons: trends, complementarities and competition, 15th Panhellenic Conference on Informatics (PCI) 2011.