A Graded Schur Lemma and a graded-monoidal structure for induced modules over graded-commutative algebras
arXiv:2403.10366 · doi:10.1080/00927872.2025.2472241
Abstract
We consider algebras and Frobenius algebras, internal to a monoidal category, that are graded over a finite abelian group. For the case that A is a twisted group algebra in a linear abelian monoidal category we obtain a graded generalization of the Schur Lemma for the category of induced A-modules. We further show that if the monoidal category is braided and A is commutative up to a bicharacter of the grading group, then the category of induced A-modules can be endowed with a graded-monoidal structure that is twisted by the bicharacter. In the particular case that the grading group is Z/2Z, these findings reproduce known results about superalgebras and super-monoidal structures.
v2: typos corrected, new remarks 2.22 and 2.39