Time-dependent community structure in legislation cosponsorship networks in the Congress of the Republic of Peru

TL;DR

This paper analyzes the dynamic community structure of legislation cosponsorship networks in Peru's Congress using multilayer network models and modularity maximization, revealing political shifts and opportunist behaviors over 2006-2011.

Contribution

It introduces a multilayer network approach to study temporal community structures in legislative networks, highlighting power shifts and legislator behaviors.

Findings

Detected power shifts in Peruvian Congress (2006-2011)

Identified emergence of opportunists switching communities

Found cohesive communities with stable members

Abstract

We study community structure in time-dependent legislation cosponsorship networks in the Peruvian Congress, and we compare them briefly to legislation cosponsorship networks in the US Senate. To study these legislatures, we employ a multilayer representation of temporal networks in which legislators in each layer are connected to each other with a weight that is based on how many bills they cosponsor. We then use multilayer modularity maximization to detect communities in these networks. From our computations, we are able to capture power shifts in the Peruvian Congress during 2006--2011. For example, we observe the emergence of 'opportunists', who switch from one community to another, as well as cohesive legislative communities whose initial component legislators never change communities. Interestingly, many of the opportunists belong to the group that won the majority in Congress.