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REGULAR ALGEBRAS OF DIMENSION 4 AND THEIR A∞-EXT-ALGEBRAS

We construct four families of Artin-Schelter regular algebras of global dimension four. This is a complete list of Artin-Schelter regular algebras of global dimension four that are generated by two elements of degree 1 and whose Ext-algebra satisfies certain “generic” conditions. These algebras are also strongly noetherian, Auslander regular and Cohen-Macaulay. One of the main tools is Keller’s higher-multiplication theorem on A∞-Ext-algebras.