We give a unified proof of Gabriel-Ulmer duality for locally finitely presentable categories, Adamek-Lawvere-Rosicky duality for varieties and Morita duality for presheaf categories. As an application, we compare presheaf categories and varieties.
Theory and Applications of Categories, Vol. 10, 2002, No. 20, pp 486-497 http://www.tac.mta.ca/tac/volumes/10/20/10-20.dvi http://www.tac.mta.ca/tac/volumes/10/20/10-20.ps http://www.tac.mta.ca/tac/volumes/10/20/10-20.pdf ftp://ftp.tac.mta.ca/pub/tac/html/volumes/10/20/10-20.dvi ftp://ftp.tac.mta.ca/pub/tac/html/volumes/10/20/10-20.psTAC Home