2026/07/20 by Dawei Shen
#math.RT
Let R be a left and right Noetherian ring. We introduce a Serre-type condition (Gn), formulated in terms of the first occurrence and the flat dimension of indecomposable injective modules, and prove that R is n-Gorenstein if and only if it satisfies (Gn). We then apply the criterion to Nakayama algebras via syzygy filtration. It is shown that syzygy filtration preserves the Auslander-Gorenstein property and reflects it within the class of 2-Gorenstein Nakayama algebras. Combined with a result of Klász, Kleinau and Marczinzik, this shows that simple modules of odd grade over Auslander-Gorenstein Nakayama algebras are regular in their grade, thereby settling their conjecture.