On the normality of arithmetical constants

Bailey and Crandall recently formulated "Hypothesis A", a general principle to explain the (conjectured) normality of the binary expansion of constant s like pi and other related numbers, or more generally the base b expansion of such constants for an integer b greater than or equal to 2. This paper shows that a basic mechanism underlying their principle, which is a relatio n between single orbits of two discrete dynamical systems, holds for a very general class of representations of numbers. This general class includes n umbers for which the conclusion of Hypothesis A is not true. The paper also relates the particular class of arithmetical constants treated by Bailey a nd Crandall to special values of G-functions, and points out an analogy of Hypothesis A with Furstenberg's conjecture on invariant measures.