An important problem in ergodic theory is to determine when the restriction to a subgroup of
an ergodic action of a group is still ergodic. Classical results concerning the ergodicity of …

A well-known class of flows arises as follows: Let G be a semisimple Lie group and F be a
lattice in G, that is, F is a discrete subgroup such that G/F admits a finite measure invariant …

In this paper we discuss the use of dynamical and ergodic-theoretic ideas and methods to
solve some long-standing problems originating from Lie groups and number theory. These …

Section 1. Let M be a Borel space, and let H be a locally compact group which is separable
in the sense of the second axiom of countability. We shall assume that M is analytic (see …

Let G be a connected Lie group and let Γ be a lattice in G (not necessarily co-compact). We
show that if (ut) is a unipotent one-parameter subgroup of G then every ergodic invariant …

In this paper we shall study extensions in the theory of ergodic actions ofa locally compact
group. If G isa locally compact group, by an ergodic G-space we mean a Lebesgue space …

A conference on the interaction of ergodic theory, differential geometry and the theory of Lie
Groups was held at the Mathematical Sciences Research Institute from May 24 to June 1 …

Let G be a connected Lie group, F be a lattice in G and U={ut},~ R be a unipotent one-
parameter subgroup of G, viz. Adu is a unipotent linear transformation for all u~ U. Consider …

1. Introduction.-In this note we shall show how two programs announced earlier may be
extended and partially unified by means of the concept of an" ergodic groupoid." The first of …

Rigidity and cocycles for ergodic actions of semi-simple lie groups Page 1 S6minaire
BOURBAKI 32e annie, 1979/80, n 559 559-O1 Juin 1980 RIGIDITY AND COCYCLES FOR …