The Journal of Symbolic Logic http://journals.cambridge.org/JSL Additional services for The Journal of Symbolic Logic: Email alerts: Click here Subscriptions: Click here Commercial reprints: Click here Terms of use : Click here Perfect extensions and derived algebras Hajnal Andréka, Steven Givant and István Németi The Journal of Symbolic Logic / Volume 60 / Issue 03 / September 1995, pp 775 - 796 DOI: 10.2307/2275756, Published online: 12 March 2014 Link to this article: http://journals.cambridge.org/abstract_S0022481200018260 How to cite this article: Hajnal Andréka, Steven Givant and István Németi (1995). Perfect extensions and derived algebras . The Journal of Symbolic Logic, 60, pp 775-796 doi:10.2307/2275756 Request Permissions : Click here Downloaded from http://journals.cambridge.org/JSL, IP address: 140.182.176.13 on 12 May 2015