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Tilting complexes for group graded algebras. II. (English) Zbl 1087.20010

[For part I cf. J. Group Theory 6, No. 2, 175-193 (2003; Zbl 1037.20001).]
The paper under review is concerned with equivalences between symmetric algebras (over an algebraically closed field \(k\)) graded by a finite group \(G\). The equivalences are between stable, homotopy and derived module categories. Several results are extended from the ungraded to the graded setting. We mention one of these: Let \(R=\bigoplus_{g\in G}R_g\) be a symmetric crossed product, let \(I\) be a finite \(G\)-set, and let \(X_i \in{\mathcal D}^b (R_1\text{-mod})\), \(i\in I\), be objects satisfying (a) \(\operatorname{Hom}(X_i,X_i[m])=0\) for \(m<0\), (b) \(\operatorname{Hom}(X_i,X_i)=k\) and \(\operatorname{Hom}(X_i,X_j)=0\) for \(i\neq j\), (c) \(X_i\), \(i\in I\), generate \({\mathcal D}^b(R_1\text{-mod})\) as a triangulated category, (d) \(R_g\otimes_{R_1}X_i \cong X_{gi}\) in \({\mathcal D}^b(R_1\text{-mod})\) for \(g\in G\). Then there are a symmetric crossed product \(R'=\bigoplus_{g\in G}R_g'\) and a \(G\)-graded derived equivalence between \(R\) and \(R'\) whose restriction to \(R_1\) sends \(X_i\), \(i\in I\), to the simple \(R_1'\)-modules.

MSC:

20C20 Modular representations and characters
20C05 Group rings of finite groups and their modules (group-theoretic aspects)
16W50 Graded rings and modules (associative rings and algebras)
18E30 Derived categories, triangulated categories (MSC2010)
16S35 Twisted and skew group rings, crossed products
16E30 Homological functors on modules (Tor, Ext, etc.) in associative algebras

Citations:

Zbl 1037.20001