Abstract We consider discrete onedimensional Schrödinger operators whose potentials are generated by sampling along the orbits of a general hyperbolic transformation. Specifically, we show that if the sampling function is a nonconstant Hölder continuous function defined on a subshift of finite type with a fully supported ergodic measure admitting a local product structure and a fixed point, then the Lyapunov exponent is positive away from a discrete set of energies. Moreover, for sampling functions in a residual subset of the space of Hölder continuous functions, the Lyapunov exponent is positive everywhere. If we consider locally constant or globally fiber bunched sampling functions, then the Lyapuonv exponent is positive away from a finite set. Moreover, for sampling functions in an open and dense subset of the space in question, the Lyapunov exponent is uniformly positive. Our results can be applied to any subshift of finite type with ergodic measures that are equilibrium states of Hölder continuous potentials. In particular, we apply our results to Schrödinger operators defined over expanding maps on the unit circle, hyperbolic automorphisms of a finitedimensional torus, and Markov chains.
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Local Asymptotics for Orthonormal Polynomials on the Unit Circle Via Universality
Letbe a positive measure on the unit circle that is regularin the sense of Stahl, Totik, and Ullmann. Assume that in some subarcJ,is absolutely continuous, while0is positive and continuous. Letf'ngbe the orthonormal polynomials for. We show that for appropriaten2J,'n(n(1+zn))'n(n)n1is a normal family in compact subsets ofC. Usinguniversality limits, we show that limits of subsequences have the formez+C(ez
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 Award ID(s):
 1800251
 NSFPAR ID:
 10215809
 Date Published:
 Journal Name:
 Journal d'Analyse Mathematique (it won't recognize the journal)
 Volume:
 141
 Page Range / eLocation ID:
 285304.
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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