To each multiquiver Γ we attach a solution to the consistency equations associated to twisted generalized Weyl (TGW) algebras. This generalizes several previously obtained solutions in the literature. We show that the corresponding algebras (Γ) carry a canonical representation by differential operators and that (Γ) is universal among all TGW algebras with such a representation. We also find explicit conditions in terms of Γ for when this representation is faithful or locally surjective.By forgetting some of the structure of Γ one obtains a Dynkin diagram, D(Γ). We show that the generalized Cartan matrix of (Γ) coincides with the one corresponding to D(Γ) and that (Γ) contains graded homomorphic images of the enveloping algebra of the positive and negative part of the corresponding Kac-Moody algebra.Finally, we show that a primitive quotient U/J of the enveloping algebra of a finitedimensional simple Lie algebra over an algebraically closed field of characteristic zero is graded isomorphic to a TGW algebra if and only if J is the annihilator of a completely pointed (multiplicity-free) simple weight module. The infinite-dimensional primitive quotients in types A and C are closely related to (Γ) for specific Γ. We also prove one result in the affine case. 6 Appendix: Relation to a previous family of TGW algebras 36
Contents1 Preliminaries
IntroductionTwisted generalized Weyl (TGW) algebras were introduced by Mazorchuk and Turowska in 1999 [15]. They are constructed from a commutative unital ring , an associative unital -algebra R, a collection of elements t = {t i } i∈I from the center of R, a collection of commutingautomorphisms σ = {σ i } i∈I of R, and a scalar matrix µ = (µ i j ) i, j∈I , by adjoining to R new non-commuting generators X i and Y i for i ∈ I, imposing some relations and taking the quotient by a certain radical (see Section 1.3 for the full definition). These algebras are denoted by µ (R, σ, t). They are naturally graded by the free abelian group on the index set I and come with a canonical map R → µ (R, σ, t) making them R-rings. In addition, if µ is symmetric, they can be equipped with an involution.The In a GWA one has X i X j = X j X i and Y i Y j = Y j Y i for all i, j. These relations need not hold in a general TGW algebra, where instead they are replaced by higher degree Serre-type relations [10].A question of particular importance is whether a given input datum (R, σ, t) actually gives rise to a non-trivial TGW algebra. Indeed, it can happen that the relations are contradictory so that µ (R, σ, t) = {0}, the algebra with one element [8, Ex. 2.8]. This does not occur for higher rank GWAs, as the conditions (1.1) implies the algebra is consistent. Thus it becomes important to find a substitute for (1.1) which ensures that a given TGW algebra is non-trivial. This question was solved in [8], in the case when the t i are not zero-divisors in R. The answer is the following.
Theorem ([8]). Assume that the elements t i are not zero-divisors in R.Then the following set of equations is sufficient fo...