Classification conjecture for finite-dimensional graded *-simple algebras

Let GG be a finite abelian group and let F~\widetilde{F} be an algebraically closed field of characteristic zero. For a finite-dimensional GG-graded algebra AA with graded involution, write AA as *-graded simple when it has no nonzero proper graded ideals invariant under the involution. Let HH be a subgroup of GG, let ζ:H×HQ[1m]\zeta:H\times H\to\mathbb{Q}[\sqrt[\mathfrak{m}]{1}]^* be a 2-cocycle, and set m=G\mathfrak{m}=|G|. Define F~ζ[H]\widetilde{F}^{\zeta}[H] as the corresponding twisted group algebra, C~(1)=Mk(F~ζ[H])\widetilde{C}^{(1)}=M_k(\widetilde{F}^{\zeta}[H]), and B=Mk(F~ζ[H])\mathcal{B}=M_k(\widetilde{F}^{\zeta}[H]).

Classification conjecture. The algebra AA is *-graded simple if and only if it is isomorphic as a graded *-algebra either to the GG-graded simple algebra C~(1)\widetilde{C}^{(1)} with an elementary involution, or to C~(2)=B×Bop\widetilde{C}^{(2)}=\mathcal{B}\times\mathcal{B}^{op} with the exchange involution ˉ\bar{*}, where Bop\mathcal{B}^{op} is the opposite algebra and ζ\zeta has values in the algebraic extension of Q\mathbb{Q} obtained by adjoining a primitive m\mathfrak{m}-th root of unity.

This is the classification assumption referred to in the surrounding text. The paper states that it is known for cyclic groups of prime order and for the group of order 44, while the general finite abelian case is presented as an assumption and remains open in the supplied text.

Sources & referencesView supporting material

Primary source

Irina Sviridova, “Identities of finitely generated graded algebras with involution”, arXiv:1410.2222 (2014).

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