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In political science, coexistence^[1] involves different voters using different electoral systems depending on which electoral district they belong to.^[2] This is distinct from other mixed electoral systems that use parallel voting (superposition) or compensatory voting. For example, the rural-urban proportional (RUP) proposal for British Columbia involved the use of a fully proportional system of list-PR or STV in urban regions, combined with MMP in rural regions.^[3]

Coexistence of electoral systems exist in multiple countries, like the Democratic Republic of the Congo and Panama, as well as for elections of the European Parliament.^{[citation needed]}. Historically, variants have been used in Iceland (1946–1959), Niger (1993, 1995) and Madagascar (1998).^[4]

^ Massicotte & Blais (1999). "Mixed electoral systems: a conceptual and empirical survey". Electoral Studies. 18 (3): 341–366. doi:10.1016/S0261-3794(98)00063-8.
^ Herron, Erik S; Nishikawa, Misa (2001-03-01). "Contamination effects and the number of parties in mixed-superposition electoral systems". Electoral Studies. 20 (1): 63–86. doi:10.1016/S0261-3794(00)00002-0. ISSN 0261-3794.
^ Massicotte, Louis (2004). In Search of Compensatory Mixed Electoral System for Québec (PDF) (Report).
^ Golder, Matt (2005-03-01). "Democratic electoral systems around the world, 1946–2000". Electoral Studies. 24 (1): 103–121. doi:10.1016/j.electstud.2004.02.008. ISSN 0261-3794.