The Greek Parliament of 2012: Coalition Formations&Power Indices in Context

The twin elections of 2012 in Greece had a manifest impact on the political scene of Greece and the European Union. In this paper we analyze the negotiations that took place after the May 06, 2012 and June 12, 2012 Parliamentary elections from a game-theoretic perspective. We model the different instances of the Parliament as weighted majority games and apply the Shapley-Shubik, Penrose-Banzhaf, Deegan-Packel and Public Good (Holler) indices. In this retrospective analysis, we aim to enhance our understanding on the reasons that led to certain outcomes in the voting processes and provide a benchmark for future comparisons in the still fluid political system and electoral framework. Our findings explain several attitudes of the political parties by comparing their P-Power and I-Power, highlight discrepancies in the distribution of power due to the disproportionality of the 2012 electoral rule and provide insight on the reasons that led both to the deadlock of the May negotiations and the fragility of the government that emerged from the June negotiations. As a further case study, we study the Presidential Elections of December 2014, that were carried by the Parliament that was elected in June 2012, and apply a method of successive re-evaluation of power indices after each round of coalition formations to understand the incentives that led to the dissolution of the Parliament. Our approach aims to offer an alternative view on existing studies about the 2012 elections and complement their findings.