Triadic motifs and dyadic self-organization in the World Trade Network

TL;DR

This paper investigates the structural properties of the World Trade Network, revealing that its self-organization is primarily encoded in dyadic reciprocity rather than simple degree sequences, through analysis of triadic motifs.

Contribution

It introduces an analytical pattern-detection method to analyze triadic motifs in the WTN and shows that reciprocity explains motif occurrence beyond degree sequences.

Findings

Motifs are not explained by degree sequences alone.

Reciprocal edges fully account for motif occurrence.

Self-organization is encoded in dyadic reciprocity.

Abstract

In self-organizing networks, topology and dynamics coevolve in a continuous feedback, without exogenous driving. The World Trade Network (WTN) is one of the few empirically well documented examples of self-organizing networks: its topology strongly depends on the GDP of world countries, which in turn depends on the structure of trade. Therefore, understanding which are the key topological properties of the WTN that deviate from randomness provides direct empirical information about the structural effects of self-organization. Here, using an analytical pattern-detection method that we have recently proposed, we study the occurrence of triadic "motifs" (subgraphs of three vertices) in the WTN between 1950 and 2000. We find that, unlike other properties, motifs are not explained by only the in- and out-degree sequences. By contrast, they are completely explained if also the numbers of reciprocal edges are taken into account. This implies that the self-organization process underlying the evolution of the WTN is almost completely encoded into the dyadic structure, which strongly depends on reciprocity.