Let S be an ergodic measure-preserving automorphism on a non-atomic
probability space, and let T be the time-one map of a topologically weak mixing
suspension flow over an irreducible subshift of finite type under a Holder
ceiling function. We show that if the measure-theoretic entropy of the S is
strictly less than the topological entropy of T, then there exists an embedding
from the measure-preserving automorphism into the suspension flow.
Let Pi and Gamma be homogeneous Poisson point processes on a fixed set of
finite volume. We prove a necessary and sufficient condition on the two
intensities for the existence of a coupling of Pi and Gamma such that Gamma is
a deterministic function of Pi, and all points of Gamma are points of Pi. The
condition exhibits a surprising lack of monotonicity. However, in the limit of
large intensities, the coupling exists if and only if the expected number of
points is at least one greater in Pi than in Gamma.
Given a homogeneous Poisson process on R^d with intensity L, we prove that it
is possible to partition the points into two sets, as a deterministic function
of the process, and in an isometry-equivariant way, so that each set of points
forms a homogeneous Poisson process, with any given pair of intensities summing
to L. In particular, this answers a question of Ball, who proved that in d=1,
the Poisson points may be similarly partitioned (via a translation-equivariant
function) so that one set forms a Poisson process of lower intensity, and asked
whether the same was possible for all d.