English

Graded Imbeddings in Finite Dimensional Simple Graded Algebras

Rings and Algebras 2024-10-18 v1

Abstract

Let F\mathbb{F} be a field and G\mathsf{G} a group. This work is inspired in the following problem: "{\it given a division (simple) G\mathsf{G}-graded F\mathbb{F}-algebra, is there any other division (simple) G\mathsf{G}-graded F\mathbb{F}-algebra such that the former can be G\mathsf{G}-imbedded in the latter?}". In this work, we answer this question affirmatively for F\mathbb{F} algebraically closed, G\mathsf{G} finite abelian, and associative algebras of finite dimension. To prove this, we apply concepts and properties of Group Cohomology. We show H2(H,F)=resHG(H2(G,F))\mathcal{H}^2(H, \mathbb{F}^*)=\mathsf{res}^\mathsf{G}_H \left(\mathcal{H}^2(\mathsf{G}, \mathbb{F}^*)\right), where HH is a subgroup of G\mathsf{G} and resHG\mathsf{res}^\mathsf{G}_H is the restriction homomorphism. Posteriorly, we prove that, given any H1,H2GH_1,H_2\leq\mathsf{G} and σiZ2(Hi,F)\sigma_i\in\mathcal{Z}^2(H_i,\mathbb{F}^*), i=1,2i=1,2, are equivalent: i) Fσ1[H1]GFσ2[H2]\mathbb{F}^{\sigma_1}[H_1] \stackrel{\mathsf{G}}{\hookrightarrow} \mathbb{F}^{\sigma_2}[H_2]; ii) H1H2H_1\leq H_2 and [σ1]=[σ2]H1[\sigma_1]=[\sigma_2]_{H_1}; iii) TG(Fσ2[H2])TG(Fσ1[H1])\mathsf{T}^{\mathsf{G}}(\mathbb{F}^{\sigma_2}[H_2])\subseteq \mathsf{T}^{\mathsf{G}}(\mathbb{F}^{\sigma_1}[H_1]), where TG(Fσi[Hi])\mathsf{T}^{\mathsf{G}}(\mathbb{F}^{\sigma_i}[H_i]) is the G\mathsf{G}T-ideal of graded identities of Fσi[Hi]\mathbb{F}^{\sigma_i}[H_i]. Furthermore, we prove that, given A\mathfrak{A} and B\mathfrak{B} two finite dimensional simple G\mathsf{G}-graded F\mathbb{F}-algebras, if F\mathbb{F} is algebraically closed, char(F)=0\mathsf{char}(\mathbb{F}) = 0 or char(F)\mathsf{char} (\mathbb{F}) is coprime with the order of each finite subgroup of G\mathsf{G}, and any subgroup of G\mathsf{G} is normal, then TG(A)TG(B)\mathsf{T}^{\mathsf{G}}(\mathfrak{A})\subseteq \mathsf{T}^{\mathsf{G}}(\mathfrak{B}) iff BGA\mathfrak{B} \stackrel{\mathsf{G}}{\hookrightarrow} \mathfrak{A}.

Keywords

Cite

@article{arxiv.2410.13183,
  title  = {Graded Imbeddings in Finite Dimensional Simple Graded Algebras},
  author = {Antonio de França},
  journal= {arXiv preprint arXiv:2410.13183},
  year   = {2024}
}