Published online by Cambridge University Press: 20 November 2018
In recent work of E. Arthurs and L. A. Shepp on a problem of H. Dym concerning the existence of an ergodic stationary stochastic process with zero entropy (cf. 1), the function dθ(n) was introduced as follows:
For an irrational number θ, let
be the sequence of points {lθ}, 1 ≦ l ≦ n, (where {x} denotes x — [x], the fractional part of x) and define*
dθ(n) = max(ai — ai-1), 1 ≦ in + 1.
It should be noted that the related function d′θ(n) = min1≤i≤n+1(ai — ai-1) has been extensively studied by Sόs, Halton, and others (cf. 2; 4; 5; 6; 7; 8; and 9).