Ergodicity and extremality of AMS sources and channels.
Let α be an ergodic rotation of the d-torus . For any piecewise smooth function with sufficiently regular pieces the unitary operator Vh(x) = exp(2π if(x))h(x + α) acting on is shown to have a continuous non-Dirichlet spectrum if the gradient of f has nonzero integral. In particular, the resulting skew product must be ergodic. If in addition α is sufficiently well approximated by rational vectors and f is represented by a linear function with noninteger coefficients then the spectrum of V...
This article is concerned with the study of the discrete version of generalized ergodic Calderón-Zygmund singular operators. It is shown that such discrete ergodic singular operators for a class of superadditive processes, namely, bounded symmetric admissible processes relative to measure preserving transformations, are weak (1,1). From this maximal inequality, a.e. existence of the discrete ergodic singular transform is obtained for such superadditive processes. This generalizes the well-known...
We extend Champernowne’s construction of normal numbers to base b to the case and obtain an explicit construction of a generic point of the shift transformation of the set .
Diagonal metric subgroups of the metric centralizer of group extensions are investigated. Any diagonal compact subgroup Z of is determined by a compact subgroup Y of a given metric compact abelian group X, by a family , of group automorphisms and by a measurable function f:X → G (G a metric compact abelian group). The group Z consists of the triples , y ∈ Y, where , x ∈ X.