Below are my completed projects with arxiv links. Also consider checking out the following pages:
- (w/ Phuong Ho) Fixed rings of quantum generalized Weyl algebras.
Generalized Weyl Algebras (GWAs) appear in diverse areas of mathematics including mathematical physics, noncommutative algebra, and representation theory. We study the invariants of quantum GWAs under finite automorphisms. We extend a theorem of Jordan and Wells and apply it to determine the fixed ring of quantum GWAs under diagonal automorphisms. We further study properties of the fixed rings, including global dimension, rigidity, and simplicity.
- (w/ Zachary Cline) Actions of quantum linear spaces on quantum algebras.
We study actions of bosonizations of quantum linear spaces on quantum algebras. Under mild conditions, we completely classify actions on quantum affine spaces and quantum matrix algebras. In the former case, it is shown that all actions of generalized Taft algebras are trivial extensions of actions on quantum planes.
- (w/ Luigi Ferraro and Robert Won) Simple ℤ-graded domains of Gelfand-Kirillov dimension two.
Let 𝕜 be an algebraically closed field and A a ℤ-graded finitely generated simple 𝕜-algebra which is a domain of Gelfand-Kirillov dimension 2. We show that the category of ℤ-graded right $A$-modules is equivalent to the category of quasicoherent sheaves on a certain quotient stack. The theory of these simple algebras is closely related to that of a class of generalized Weyl algebras (GWAs). We prove a translation principle for the noncommutative schemes of these GWAs, shedding new light on the classical translation principle for the infinite-dimensional primitive quotients of U(sl2).
- (w/ Xingting Wang) The Zariski cancellation problem for Poisson algebras.
We study the Zariski cancellation problem for Poisson algebras asking whether A[x]≅B[y] implies A≅B when A and B are Poisson algebras. We resolve this affirmatively in the cases when A and B are both connected graded Poisson algebras finitely generated in degree 1 without degree one Poisson central elements and when A is a Poisson integral domain of Krull dimension two with nontrivial Poisson bracket. We further introduce the Poisson analogues of Makar-Limanov invariant and discriminant to deal with the Zariski cancellation problem for some families of Poisson algebras.
- Prime and semiprime quantum linear space smash products.
Quantum linear spaces are a large class of pointed Hopf algebras that include the Taft algebras and their generalizations. We give conditions for the smash product of an associative algebra with a quantum linear space to be (semi)prime. These are then used to determine (semi)primeness of certain smash products with quantum affine spaces. This extends Bergen's work on Taft algebras.
- (w/ Daniel Rogalski)
Quivers supporting twisted Calabi-Yau algebras. (Code)
We consider graded twisted Calabi-Yau algebras of dimension 3 which are derivation-quotient algebras of the form A = 𝕜Q/I, where Q is a quiver and I is an ideal of relations coming from taking partial derivatives of a twisted superpotential on Q. We define the type (M, P, d) of such an algebra A, where M is the incidence matrix of the quiver, P is the permutation matrix giving the action of the Nakayama automorphism of A on the vertices of the quiver, and d is the degree of the superpotential. We study the question of what possible types can occur under the additional assumption that A has polynomial growth. In particular, we are able to give a nearly complete answer to this question when Q has at most 3 vertices.
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Isomorphisms of graded path algebras.
We prove that if two path algebras with homogeneous relations are isomorphic as algebras, then they are isomorphic as graded path algebras. This extends a result by Bell and Zhang in the connected case.
- (w/ Robert Won)
Fixed rings of generalized Weyl algebras.
Journal of Algebra, 536, 2019, 149-169.
We study actions by filtered automorphisms on classical generalized Weyl algebras. In the case of a defining polynomial of degree two, we prove that the fixed ring under the action of a finite cyclic group of filtered automorphisms is again a classical GWA, extending a result of Jordan and Wells. Partial results are provided for the case of higher degree polynomials. In addition, we establish Auslander's theorem for classical GWAs and finite cyclic groups of filtered automorphisms.
- (w/ Robert Won and Daniel Yee)
Discriminants of Taft algebra smash products and applications.
Algebras and Representation Theory, 22 (4), 2019, 785-799.
A general criterion is given for when the center of a Taft algebra smash product is the fixed ring. This is applied to the study of the noncommutative discriminant. Our method relies on the Poisson methods of Nguyen, Trampel, and Yakimov, but also makes use of Poisson Ore extensions. Specifically, we fully determine the inner faithful actions of Taft algebras on quantum planes and quantum Weyl algebras. We compute the discriminant of the corresponding smash product and apply it to compute the Azumaya locus and restricted automorphism group.
- (w/ Daniel Yee)
Congenial algebras: Extensions and examples.
Communications in Algebra, 47 (10), 2019, 4347-4357.
We study the congeniality property of algebras, as defined by Bao, He, and Zhang, in order to establish a version of Auslander's theorem for various families of filtered algebras. It is shown that the property is preserved under homomorphic images and tensor products under some mild conditions. Examples of congenial algebras in this paper include enveloping algebras of Lie superalgebras, iterated differential operator rings, quantized Weyl algebras, down-up algebras, and symplectic reflection algebras.
- (w/ Ellen Kirkman, W. Frank Moore, and Robert Won)
Auslander's Theorem for permutation actions on noncommutative algebras.
Proceedings of the American Mathematical Society, 147 (5), 2019, 1881-1896.
When A = k[x_1,..., x_n] and G is a small subgroup of GL_n(k), Auslander's Theorem says that the skew group algebra A#G is isomorphic to End_{A^G}(A) as graded algebras. We prove a generalization of Auslander's Theorem for permutation actions on (-1)-skew polynomial rings, (-1)-quantum Weyl algebras, three-dimensional Sklyanin algebras, and a certain homogeneous down-up algebra. We also show that certain fixed rings A^G are graded isolated singularities in the sense of Ueyama.
- The isomorphism problem for quantum affine spaces,
homogenized quantized Weyl algebras, and quantum matrix algebras.
Journal of Pure and Applied Algebra, 221 (10), 2017, 2511-2524.
Bell and Zhang have shown that if A and B are two connected graded algebras finitely generated in degree one that are isomorphic as ungraded algebras, then they are isomorphic as graded algebras. We exploit this result to solve the isomorphism problem in the cases of quantum affine spaces, quantum matrix algebras, and homogenized multiparameter quantized Weyl algebras. Our result involves determining the degree one normal elements, factoring out, and then repeating. This creates an iterative process that allows one to determine relationships between relative parameters.
- (w/ Ellen Kirkman and W. Frank Moore)
On the discriminant of twisted tensor products.
Journal of Algebra 477, 2017, 29-55.
We provide formulas for computing the discriminant of noncommutative algebras over central subalgebras in the case of Ore extensions and skew group extensions. The formulas follow from a more general result regarding the discriminants of certain twisted tensor products. We employ our formulas to compute automorphism groups for examples in each case.
- (w/ Ken Price) Some algebras similar to
the 2x2 Jordanian matrix algebra.
Communications in Algebra, 45 (5), 2017, 2091-2104.
The impetus for this study is the work of Dumas and Rigal on the Jordanian deformation of the ring of coordinate functions on 2x2 matrices. We are also motivated by current interest in birational equivalence of noncommutative rings. Recognizing the construction of the Jordanian matrix algebra as a skew polynomial ring, we construct a family of algebras relative to differential operator rings over a polynomial ring in one variable which are birationally equivalent to the Weyl algebra over a polynomial ring in two variables.
- Two-parameter analogs of the Heisenberg enveloping algebra.
Communications in Algebra, 44 (11), 2016, 4637-4653.
One-parameter analogs of the Heisenberg enveloping algebra were studied previously by Kirkman and Small. In particular, they demonstrated how one may obtain Hayashi's analog of the Weyl algebra as a primitive factor of this algebra. We consider various two-parameter versions of this problem. Of particular interest is the case when the parameters are dependent. Our study allows us to consider the representation theory of a two-parameter version of the Virasoro enveloping algebra.
- PBW deformations of Artin-Schelter regular algebras.
Journal of Algebra and Its Applications, 15 (4), 2016.
We consider algebras that can be realized as PBW deformations of (Artin-Schelter) regular algebras. This is equivalent to the homogenization of the algebra being regular. It is shown that the homogenization, when it is a geometric algebra, contains a component whose points are in 1-1 correspondence with the simple modules of the deformation. We classify all PBW deformations of 2-dimensional regular algebras and give examples of 3-dimensional deformations. Other properties, such as the skew Calabi-Yau property and closure under tensor products, are considered.
- Two-generated algebras and standard-form congruence.
Communications in Algebra, 43 (4), 2015, 1668-1686.
Matrix congruence can be used to mimic linear maps between homogeneous quadratic polynomials in n variables. We introduce a generalization, called standard-form congruence, which mimics affine maps between non-homogeneous quadratic polynomials. Canonical forms under standard-form congruence for three-by-three matrices are derived. This is then used to give a classification of algebras defined by two generators and one degree two relation. We also apply standard-form congruence to classify homogenizations of these algebras.
- Isomorphisms of some quantum spaces.
Ring Theory and Its Applications, Contemp. Math., 609, Amer. Math. Soc., 2014, 107-116.
We consider a series of questions that grew out of determining when two quantum planes are isomorphic. In particular, we consider a similar question for quantum matrix algebras and certain ambiskew polynomial rings. Additionally, we modify a result by Alev and Dumas to show that two quantum Weyl algebras are isomorphic if and only if their parameters are equal or inverses of each other.
- Dissertation: PBW deformations of Artin-Schelter regular algebras and their homogenizations (Slides)