A Generating Function Approach to the Enumeration of Matrices in Classical Groups over Finite Fields

A Generating Function Approach to the Enumeration of Matrices in Classical Groups over Finite Fields
Author: Jason Fulman
Publisher: American Mathematical Soc.
Total Pages: 104
Release: 2005
Genre: Mathematics
ISBN: 0821837060

Generating function techniques are used to study the probability that an element of a classical group defined over a finite field is separable, cyclic, semisimple or regular. The limits of these probabilities as the dimension tends to infinity are calculated in all cases, and exponential convergence to the limit is proved. These results complement and extend earlier results of the authors, G. E. Wall, and Guralnick & Lubeck.

On Boundary Interpolation for Matrix Valued Schur Functions

On Boundary Interpolation for Matrix Valued Schur Functions
Author: Vladimir Bolotnikov
Publisher: American Mathematical Soc.
Total Pages: 122
Release: 2006
Genre: Mathematics
ISBN: 0821840479

A number of interpolation problems are considered in the Schur class of $p\times q$ matrix valued functions $S$ that are analytic and contractive in the open unit disk. The interpolation constraints are specified in terms of nontangential limits and angular derivatives at one or more (of a finite number of) boundary points. Necessary and sufficient conditions for existence of solutions to these problems and a description of all the solutions when these conditions are met is given.The analysis makes extensive use of a class of reproducing kernel Hilbert spaces ${\mathcal{H (S)$ that was introduced by de Branges and Rovnyak. The Stein equation that is associated with the interpolation problems under consideration is analyzed in detail. A lossless inverse scattering problem isalso considered.

A Categorical Approach to Imprimitivity Theorems for $C^*$-Dynamical Systems

A Categorical Approach to Imprimitivity Theorems for $C^*$-Dynamical Systems
Author: Siegfried Echterhoff
Publisher: American Mathematical Soc.
Total Pages: 186
Release: 2006
Genre: Mathematics
ISBN: 0821838571

It has become apparent that studying the representation theory and structure of crossed-product C*-algebras requires imprimitivity theorems. This monograph shows that the imprimitivity theorem for reduced algebras, Green's imprimitivity theorem for actions of groups, and Mansfield's imprimitivity theorem for coactions of groups can all be understoo

Invariant Means and Finite Representation Theory of $C^*$-Algebras

Invariant Means and Finite Representation Theory of $C^*$-Algebras
Author: Nathanial Patrick Brown
Publisher: American Mathematical Soc.
Total Pages: 122
Release: 2006
Genre: Mathematics
ISBN: 0821839160

Various subsets of the tracial state space of a unital C$*$-algebra are studied. The largest of these subsets has a natural interpretation as the space of invariant means. II$ 1$-factor representations of a class of C$*$-algebras considered by Sorin Popa are also studied. These algebras are shown to have an unexpected variety of II$ 1$-factor representations. In addition to developing some general theory we also show that these ideas are related to numerous other problems inoperator algebras.

Integrable Hamiltonian Systems on Complex Lie Groups

Integrable Hamiltonian Systems on Complex Lie Groups
Author: Velimir Jurdjevic
Publisher: American Mathematical Soc.
Total Pages: 150
Release: 2005
Genre: Mathematics
ISBN: 0821837648

Studies the elastic problems on simply connected manifolds $M_n$ whose orthonormal frame bundle is a Lie group $G$. This title synthesizes ideas from optimal control theory, adapted to variational problems on the principal bundles of Riemannian spaces, and the symplectic geometry of the Lie algebra $\mathfrak{g}, $ of $G$

Quasi-Ordinary Power Series and Their Zeta Functions

Quasi-Ordinary Power Series and Their Zeta Functions
Author: Enrique Artal-Bartolo
Publisher: American Mathematical Soc.
Total Pages: 98
Release: 2005
Genre: Mathematics
ISBN: 0821838768

Intends to prove the monodromy conjecture for the local Igusa zeta function of a quasi-ordinary polynomial of arbitrary dimension defined over a number field. In order to do it, this title computes the local Denef-Loeser motivic zeta function $Z_{\text{DL}}(h, T)$ of a quasi-ordinary power series $h$ of arbitrary dimension

Tangential Boundary Stabilization of Navier-Stokes Equations

Tangential Boundary Stabilization of Navier-Stokes Equations
Author: Viorel Barbu
Publisher: American Mathematical Soc.
Total Pages: 146
Release: 2006
Genre: Mathematics
ISBN: 0821838741

In order to inject dissipation as to force local exponential stabilization of the steady-state solutions, an Optimal Control Problem (OCP) with a quadratic cost functional over an infinite time-horizon is introduced for the linearized N-S equations. As a result, the same Riccati-based, optimal boundary feedback controller which is obtained in the linearized OCP is then selected and implemented also on the full N-S system. For $d=3$, the OCP falls definitely outside the boundaries of established optimal control theory for parabolic systems with boundary controls, in that the combined index of unboundedness--between the unboundedness of the boundary control operator and the unboundedness of the penalization or observation operator--is strictly larger than $\tfrac{3}{2}$, as expressed in terms of fractional powers of the free-dynamics operator. In contrast, established (and rich) optimal control theory [L-T.2] of boundary control parabolic problems and corresponding algebraic Riccati theory requires a combined index of unboundedness strictly less than 1. An additional preliminary serious difficulty to overcome lies at the outset of the program, in establishing that the present highly non-standard OCP--with the aforementioned high level of unboundedness in control and observation operators and subject, moreover, to the additional constraint that the controllers be pointwise tangential--be non-empty; that is, it satisfies the so-called Finite Cost Condition [L-T.2].

Stability of Spherically Symmetric Wave Maps

Stability of Spherically Symmetric Wave Maps
Author: Joachim Krieger
Publisher: American Mathematical Soc.
Total Pages: 96
Release: 2006
Genre: Mathematics
ISBN: 0821838776

Presents a study of Wave Maps from ${\mathbf{R}}^{2+1}$ to the hyperbolic plane ${\mathbf{H}}^{2}$ with smooth compactly supported initial data which are close to smooth spherically symmetric initial data with respect to some $H^{1+\mu}$, $\mu>0$.

The Role of True Finiteness in the Admissible Recursively Enumerable Degrees

The Role of True Finiteness in the Admissible Recursively Enumerable Degrees
Author: Noam Greenberg
Publisher: American Mathematical Soc.
Total Pages: 114
Release: 2006
Genre: Mathematics
ISBN: 0821838857

When attempting to generalize recursion theory to admissible ordinals, it may seem as if all classical priority constructions can be lifted to any admissible ordinal satisfying a sufficiently strong fragment of the replacement scheme. We show, however, that this is not always the case. In fact, there are some constructions which make an essential use of the notion of finiteness which cannot be replaced by the generalized notion of $\alpha$-finiteness. As examples we discuss bothcodings of models of arithmetic into the recursively enumerable degrees, and non-distributive lattice embeddings into these degrees. We show that if an admissible ordinal $\alpha$ is effectively close to $\omega$ (where this closeness can be measured by size or by cofinality) then such constructions maybe performed in the $\alpha$-r.e. degrees, but otherwise they fail. The results of these constructions can be expressed in the first-order language of partially ordered sets, and so these results also show that there are natu