Amenable groups and nonpositively curved
spaces 
PierreEmmanuel Caprace 
Let X
be a Hadamard space, namely a proper metric space of nonpositive curvature, and assume that Isom(X) acts
cocompactly on X. We present an algebraic characterization of the (possibly
nondiscrete) closed subgroups
of Isom(X) which are amenable.
