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A criterion for Gorenstein algebras to be regular. (English) Zbl 1251.16013

Let \(A\) be a left Gorenstein connected graded algebra with trivial module \(_Ak\). Assume that \(k\) admits a resolution by finitely generated free modules. The main result of the paper says that \(A\) is Artin-Schelter regular if and only if the Gorenstein index of \(A\) equals \(-\inf\{i\mid\text{Ext}_A^{\text{depth}_AA}(k,k)_i\neq 0\}\). The Gorenstein index is defined as follows. Recall that \(\text{Ext}_A^i(k,A)\) is nonzero if and only if \(i=\text{depth}_AA\), and in that case it is isomorphic to a copy of \(k\). The Gorenstein index is then defined as the internal degree of that copy.

MSC:

16E65 Homological conditions on associative rings (generalizations of regular, Gorenstein, Cohen-Macaulay rings, etc.)
16E30 Homological functors on modules (Tor, Ext, etc.) in associative algebras
16W50 Graded rings and modules (associative rings and algebras)
16E50 von Neumann regular rings and generalizations (associative algebraic aspects)
Full Text: DOI

References:

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