Political Power in the Swedish Riksdag

In recent years many parliaments have become fragmented and polarized, with difficulties to form government. Traditional party alliances have changed, new parties have been established, and some of these are shunned by the traditional parties. Fragile minority governments are formed and break up. We propose a game-theoretic framework for analysis of political power in parliaments for situations when party affilations change and new coalitions are formed. More speciffically, we use and modify tools from cooperative game theory, in particular Myerson (1977) and Alonso-Meijide and Carreras (2011). The analytical framework is applied to the current Swedish parliament.