Perturbations of Orthogonal Polynomials With Periodic Recursion Coefficients

A concise expression for the ODE's of orthogonal polynomials

It is known that orthogonal polynomials obey a 3 terms recursion relation, as well as a 2x2 differential system. Here, we give an explicit and concise expression of the differential system in terms of the recursion coefficients. This result is a generalization of an expression of Fokas, Its and Kitaev for the symmetric case.

Fine structure of the zeros of orthogonal polynomials, III. Periodic recursion coefficients

We discuss asymptotics of the zeros of orthogonal polynomials on the real line and on the unit circle when the recursion coefficients are periodic. The zeros on or near the absolutely continuous spectrum have a clock structure with spacings inverse to the density of zeros. Zeros away from the a.c. spectrum have limit points mod p and only finitely many of them.

Orthogonal polynomials with exponentially decaying recursion coefficients

We review recent results on necessary and sufficient conditions for measures on $\mathbb{R}$ and $\partial\mathbb{D}$ to yield exponential decay of the recursion coefficients of the corresponding orthogonal polynomials. We include results on the relation of detailed asymptotics of the recursion coefficients to detailed analyticity of the measures. We present an analog of Carmona's formula for OPRL. A major role is played by the Szego and Jost functions.

Orthogonal Polynomials with Recursion Coefficients of Generalized Bounded Variation

We consider probability measures on the real line or unit circle with Jacobi or Verblunsky coefficients satisfying an $\ell^p$ condition and a generalized bounded variation condition. This latter condition requires that a sequence can be expressed as a sum of sequences $β^{(l)}$, each of which has rotated bounded variation, i.e., $\sum_{n=0}^\infty | e^{iϕ_l} β_{n+1}^{(l)} - β_n^{(l)} |$ is finite for some $ϕ_l$. This includes discrete Schrödinger operators on a half-line or line with finite linear combinations of Wigner--von Neumann type potentials. For the real line, we prove that in the Leb…

Limit-Periodic Verblunsky Coefficients for Orthogonal Polynomials on the Unit Circle

Avila recently introduced a new method for the study of the discrete Schrödinger Operator with limit periodic potential. I adapt this method to the context of orthogonal polynomials in the unit circle with limit periodic Verblunsky Coefficients. Specifically, I represent these Verblunsky Coefficients as a continuous sampling of the orbits of a Cantor group by a minimal translation. I then investigate the measures that arise on the unit circle as I vary the sampling function.

Jordan块情形下具有周期调制递推系数的正交多项式

Orthogonal polynomials with periodically modulated recurrence coefficients in the Jordan block case

研究了$0$位于周期Jacobi矩阵谱硬边缘时周期调制递推系数正交多项式，证明了测度的绝对连续与离散性，给出了Turán行列式密度公式、精确渐近行为及Christoffel-Darboux核标度极限。