Imaginary Schur-Weyl Duality

Imaginary Schur-Weyl Duality
Author: Alexander Kleshchev
Publisher: American Mathematical Soc.
Total Pages: 108
Release: 2017-01-18
Genre: Mathematics
ISBN: 1470422492

The authors study imaginary representations of the Khovanov-Lauda-Rouquier algebras of affine Lie type. Irreducible modules for such algebras arise as simple heads of standard modules. In order to define standard modules one needs to have a cuspidal system for a fixed convex preorder. A cuspidal system consists of irreducible cuspidal modules—one for each real positive root for the corresponding affine root system X , as well as irreducible imaginary modules—one for each -multiplication. The authors study imaginary modules by means of “imaginary Schur-Weyl duality” and introduce an imaginary analogue of tensor space and the imaginary Schur algebra. They construct a projective generator for the imaginary Schur algebra, which yields a Morita equivalence between the imaginary and the classical Schur algebra, and construct imaginary analogues of Gelfand-Graev representations, Ringel duality and the Jacobi-Trudy formula.

Applications of Polyfold Theory I: The Polyfolds of Gromov-Witten Theory

Applications of Polyfold Theory I: The Polyfolds of Gromov-Witten Theory
Author: H. Hofer
Publisher: American Mathematical Soc.
Total Pages: 230
Release: 2017-07-13
Genre: Mathematics
ISBN: 1470422034

In this paper the authors start with the construction of the symplectic field theory (SFT). As a general theory of symplectic invariants, SFT has been outlined in Introduction to symplectic field theory (2000), by Y. Eliashberg, A. Givental and H. Hofer who have predicted its formal properties. The actual construction of SFT is a hard analytical problem which will be overcome be means of the polyfold theory due to the present authors. The current paper addresses a significant amount of the arising issues and the general theory will be completed in part II of this paper. To illustrate the polyfold theory the authors use the results of the present paper to describe an alternative construction of the Gromov-Witten invariants for general compact symplectic manifolds.

Knot Invariants and Higher Representation Theory

Knot Invariants and Higher Representation Theory
Author: Ben Webster
Publisher: American Mathematical Soc.
Total Pages: 154
Release: 2018-01-16
Genre: Mathematics
ISBN: 1470426501

The author constructs knot invariants categorifying the quantum knot variants for all representations of quantum groups. He shows that these invariants coincide with previous invariants defined by Khovanov for sl and sl and by Mazorchuk-Stroppel and Sussan for sl . The author's technique is to study 2-representations of 2-quantum groups (in the sense of Rouquier and Khovanov-Lauda) categorifying tensor products of irreducible representations. These are the representation categories of certain finite dimensional algebras with an explicit diagrammatic presentation, generalizing the cyclotomic quotient of the KLR algebra. When the Lie algebra under consideration is sl , the author shows that these categories agree with certain subcategories of parabolic category for gl .

Rationality Problem for Algebraic Tori

Rationality Problem for Algebraic Tori
Author: Akinari Hoshi
Publisher: American Mathematical Soc.
Total Pages: 228
Release: 2017-07-13
Genre: Mathematics
ISBN: 1470424096

The authors give the complete stably rational classification of algebraic tori of dimensions and over a field . In particular, the stably rational classification of norm one tori whose Chevalley modules are of rank and is given. The authors show that there exist exactly (resp. , resp. ) stably rational (resp. not stably but retract rational, resp. not retract rational) algebraic tori of dimension , and there exist exactly (resp. , resp. ) stably rational (resp. not stably but retract rational, resp. not retract rational) algebraic tori of dimension . The authors make a procedure to compute a flabby resolution of a -lattice effectively by using the computer algebra system GAP. Some algorithms may determine whether the flabby class of a -lattice is invertible (resp. zero) or not. Using the algorithms, the suthors determine all the flabby and coflabby -lattices of rank up to and verify that they are stably permutation. The authors also show that the Krull-Schmidt theorem for -lattices holds when the rank , and fails when the rank is ...

Property ($T$) for Groups Graded by Root Systems

Property ($T$) for Groups Graded by Root Systems
Author: Mikhail Ershov
Publisher: American Mathematical Soc.
Total Pages: 148
Release: 2017-09-25
Genre: Mathematics
ISBN: 1470426048

The authors introduce and study the class of groups graded by root systems. They prove that if is an irreducible classical root system of rank and is a group graded by , then under certain natural conditions on the grading, the union of the root subgroups is a Kazhdan subset of . As the main application of this theorem the authors prove that for any reduced irreducible classical root system of rank and a finitely generated commutative ring with , the Steinberg group and the elementary Chevalley group have property . They also show that there exists a group with property which maps onto all finite simple groups of Lie type and rank , thereby providing a “unified” proof of expansion in these groups.

Orthogonal and Symplectic $n$-level Densities

Orthogonal and Symplectic $n$-level Densities
Author: A. M. Mason
Publisher: American Mathematical Soc.
Total Pages: 106
Release: 2018-02-23
Genre: Mathematics
ISBN: 1470426854

In this paper the authors apply to the zeros of families of -functions with orthogonal or symplectic symmetry the method that Conrey and Snaith (Correlations of eigenvalues and Riemann zeros, 2008) used to calculate the -correlation of the zeros of the Riemann zeta function. This method uses the Ratios Conjectures (Conrey, Farmer, and Zimbauer, 2008) for averages of ratios of zeta or -functions. Katz and Sarnak (Zeroes of zeta functions and symmetry, 1999) conjecture that the zero statistics of families of -functions have an underlying symmetry relating to one of the classical compact groups , and . Here the authors complete the work already done with (Conrey and Snaith, Correlations of eigenvalues and Riemann zeros, 2008) to show how new methods for calculating the -level densities of eigenangles of random orthogonal or symplectic matrices can be used to create explicit conjectures for the -level densities of zeros of -functions with orthogonal or symplectic symmetry, including all the lower order terms. They show how the method used here results in formulae that are easily modified when the test function used has a restricted range of support, and this will facilitate comparison with rigorous number theoretic -level density results.

Maximal Cohen-Macaulay Modules Over Non-Isolated Surface Singularities and Matrix Problems

Maximal Cohen-Macaulay Modules Over Non-Isolated Surface Singularities and Matrix Problems
Author: Igor Burban
Publisher: American Mathematical Soc.
Total Pages: 134
Release: 2017-07-13
Genre: Mathematics
ISBN: 1470425378

In this article the authors develop a new method to deal with maximal Cohen–Macaulay modules over non–isolated surface singularities. In particular, they give a negative answer on an old question of Schreyer about surface singularities with only countably many indecomposable maximal Cohen–Macaulay modules. Next, the authors prove that the degenerate cusp singularities have tame Cohen–Macaulay representation type. The authors' approach is illustrated on the case of k as well as several other rings. This study of maximal Cohen–Macaulay modules over non–isolated singularities leads to a new class of problems of linear algebra, which the authors call representations of decorated bunches of chains. They prove that these matrix problems have tame representation type and describe the underlying canonical forms.

Fundamental Solutions and Local Solvability for Nonsmooth Hormander's Operators

Fundamental Solutions and Local Solvability for Nonsmooth Hormander's Operators
Author: Marco Bramanti
Publisher: American Mathematical Soc.
Total Pages: 92
Release: 2017-09-25
Genre: Mathematics
ISBN: 1470425599

The authors consider operators of the form in a bounded domain of where are nonsmooth Hörmander's vector fields of step such that the highest order commutators are only Hölder continuous. Applying Levi's parametrix method the authors construct a local fundamental solution for and provide growth estimates for and its first derivatives with respect to the vector fields. Requiring the existence of one more derivative of the coefficients the authors prove that also possesses second derivatives, and they deduce the local solvability of , constructing, by means of , a solution to with Hölder continuous . The authors also prove estimates on this solution.

Induction, Bounding, Weak Combinatorial Principles, and the Homogeneous Model Theorem

Induction, Bounding, Weak Combinatorial Principles, and the Homogeneous Model Theorem
Author: Denis R. Hirschfeldt
Publisher: American Mathematical Soc.
Total Pages: 114
Release: 2017-09-25
Genre: Mathematics
ISBN: 1470426579

Goncharov and Peretyat'kin independently gave necessary and sufficient conditions for when a set of types of a complete theory is the type spectrum of some homogeneous model of . Their result can be stated as a principle of second order arithmetic, which is called the Homogeneous Model Theorem (HMT), and analyzed from the points of view of computability theory and reverse mathematics. Previous computability theoretic results by Lange suggested a close connection between HMT and the Atomic Model Theorem (AMT), which states that every complete atomic theory has an atomic model. The authors show that HMT and AMT are indeed equivalent in the sense of reverse mathematics, as well as in a strong computability theoretic sense and do the same for an analogous result of Peretyat'kin giving necessary and sufficient conditions for when a set of types is the type spectrum of some model.

On Operads, Bimodules and Analytic Functors

On Operads, Bimodules and Analytic Functors
Author: Nicola Gambino
Publisher: American Mathematical Soc.
Total Pages: 122
Release: 2017-09-25
Genre: Mathematics
ISBN: 1470425769

The authors develop further the theory of operads and analytic functors. In particular, they introduce the bicategory of operad bimodules, that has operads as -cells, operad bimodules as -cells and operad bimodule maps as 2-cells, and prove that it is cartesian closed. In order to obtain this result, the authors extend the theory of distributors and the formal theory of monads.