  D. Bailey and R. E. Crandall recently formulated a "Hypothesis A", which
provides a general principle to explain the (conjectured) normality of
constants like pi or log 2 and other related numbers, to base 2 or other
integer bases. This paper explains the basic mechanism behind their principle
as a connection between single orbits of two different discrete dynamical
systems. It relates a subclass of arithmetical constants they consider to
special values of G-functions, and characterizes this subclass. Finally it
notes some parallels of "Hypothesis A" with Furstenberg's conjecture on
invariant measures.
